The best window alarms, compared.
Top pick: TECKNET window and door alarm, 3-pack Best value: VOXON magnetic window alarm, 4-pack – Four sensors at about £12.74 with four LR44 cells in the bullets, 4.4 from 1,826 reviews. Updated 16 October 2026.
A window alarm on amazon.co.uk is usually a vibration puck stuck to the glass, or a two-piece magnetic contact that sounds when the window or door opens. UK shoppers use one as a local deterrent and to wake the household, not as a monitored burglar alarm. Police.uk and say an audible-only alarm is unlikely to bring officers unless there is other evidence of a crime. What matters is the event, a flat enough frame, and a siren you can hear without nightly false trips. The [window alarm buying guide](/hub/burglar-protection/window-alarm/sub/window-alarm-buying-guide) covers sensor, frame, batteries and the police limit. These units are not a BS EN 50131 system.
A window alarm on amazon.co.uk is usually a vibration puck stuck to the glass, or a two-piece magnetic contact that sounds when the window or door opens.
28 products checked · 54 hrs invested · +18,600 readers
Swipe for more
1-2 of 8
Personal buying guide
Question 1 of 2
What should set it off?
The TECKNET TK-WA801 is a three-pack magnetic alarm at about £13.99, 9.8 × 3.5 × 1 cm, that keeps sounding while the parts are more than 2 cm apart. The listing gives off, chime and alarm, plus three volume levels, and a 100 dB figure that was not measured here. amazon.co.uk lists 4.6 from 1,479 reviews. In the UK reviews read for this comparison the alarm is called loud even on the lowest volume, the three modes are used as described, and people fit them for children, a childcare door, a caravan and night security. One review says it was still working after six months. Rounded, bevelled or curved frames stop the halves meeting. The arrows are described as suited to doors that open from the left, and the listing never says whether the alkaline cells are in the box. It is the top pick for a magnetic contact on a flat frame when you want the siren turned down. It does not take the value badge, because the cells are not stated as included.
Pros
Cons
Best for: A flat frame or a door you want to hear open, when you want a volume you can turn down.
Less suitable: A bevelled uPVC edge, or a smash while the sash stays shut.
Specifications
Common questions
What do the TECKNET modes do?
Alarm sounds while the parts are more than 2 cm apart, until they meet again. Chime is a short sound. Off is silent. Volume has three levels.
Does it need a flat frame?
UK reviews say rounded, bevelled or curved edges stop the two halves meeting. The bullets say keep the sensor within 2 cm of the arrow side.
Are batteries listed as included?
The specification says alkaline batteries. It does not say how many, or that they are in the box.
The VOXON VOXON-802 is a four-pack at about £12.74, about £3.19 a sensor, that sounds when the alarm and magnet are more than 20 mm apart. The bullets include four LR44 cells and claim up to three years, with off, chime and alarm and no volume slider, and a 100 dB figure that was not measured here. amazon.co.uk lists 4.4 from 1,826 reviews, the largest count in this set. UK reviews read for this comparison call it very loud, including from another floor, and people use it for a child who can reach a latch, an older person at night, a shop door and a hotel door. There is no volume control, so the daytime chime is too loud for some. The sensor is one-sided, so a left-hand door is fitted upside down. A large door gap stops it triggering, and one pad failed overnight so the loose part sounded at 2am. It is the best value: four sensors with the cells stated in the bullets. It does not take the top-pick badge, which goes to the listing with three volume levels.
Pros
Cons
Best for: An opening on a flat frame, including a door a parent wants to hear, when you want the cells in the box.
Less suitable: Anyone who needs to turn the siren down, or a bevelled frame where the halves cannot meet.
Specifications
Common questions
Can the VOXON volume be turned down?
The listing describes off, chime and alarm. It does not describe a volume control. Reviews call the alarm very loud.
What gap sets it off?
The bullets say the siren starts when the alarm and magnet are more than 20 mm apart, and continues until the door is closed.
Are batteries included?
The bullets say four LR44 batteries are included, with a claim of up to 3 years. The specification block has no battery line.
The WER Doberman slim two-pack, part BI-SE-0106-2, is a vibration puck the bullets size at 70 × 70 × 10 mm, at about £15.97, with a 100 dB claim and three LR44 cells included. The bullets say the sensor is tuned so rain and wind do not trip it. amazon.co.uk lists 4.4 from 236 reviews. UK reviews in the sample call it very loud and slim on the glass, and still stuck after about two years in some cases, including a shed where a person left after a light went on. The same sample includes false trips from cupboards, closing car doors, condensation and heavy rain, and one pack of two in which neither unit worked. Some packs had no warning sticker on the reverse, which the bullets do not promise. The item-weight field says 100 g against a bullet of 70 g. It suits one puck on one pane if you will test it and you can accept that heavy rain has tripped at least one unit.
Pros
Cons
Best for: One puck on one pane, with cells in the box, if you will test it and you can accept that heavy rain has tripped at least one unit.
Less suitable: Four panes if you want a stated 30-second cut-off, or glass that needs a sensitivity dial.
Specifications
Common questions
Do the bullets say rain will set the WER alarm off?
The bullets say the sensor is tuned not to alarm in rain or wind. One UK review says heavy rain did set a unit off.
What size is it?
The bullets say 70 mm x 70 mm x 10 mm and 70 g. The item-weight field says 100 g. The dimension field says 7 x 7 x 1 cm.
Are batteries included?
The listing says 3 LR44 batteries are required and included.
The WOWSEA BO-8Y69-5GGR is a vibration alarm at about £27.97 with a 100 dB claim that was not measured here, a listed weight of 50 g, and bullets that say rain and wind should not trip it and that a warning sticker sits on the back. The size line says 70 × 8 × 70 mm and the item dimensions say 7 × 0.8 × 0.8 cm, and the pack field says 4 while the item field says 1. amazon.co.uk lists 4.2 from 222 reviews. UK reviews in the sample call it deafening in the same room, and a light tap is enough for many, including after an attempted break-in on a uPVC door panel. One review says the box had no sticker. A dog barking and the window cleaner set it off, and batteries are difficult to change once it is mounted. Battery count and inclusion are not stated. It can suit a single-room glass puck if you confirm what arrived before you rely on the sticker or the pack count. It is a weak comparison on price per sensor, because the listing does not settle whether you have bought one or four.
Pros
Cons
Best for: A single-room glass puck, if you can confirm what arrived in the box before you rely on the sticker or the pack count.
Less suitable: Anyone comparing price per sensor, because the listing does not settle whether you have bought one or four.
Specifications
Common questions
How many WOWSEA units are in the box?
Number of packs is 4 and number of items is 1. The title does not state a pack count. The listing does not resolve that.
Is a warning sticker included?
The bullets say there is a warning sticker on the back. One UK review says the box had none.
Which dimensions does the listing give?
Size is 70 x 8 x 70 mm. Item dimensions are 7 x 0.8 x 0.8 cm. Both figures are on the listing.
The Defender EL00231 is a two-pack vibration puck, 10 × 51 × 62 mm and 50 g, that the listing says sounds a 130 dB siren if the glass is hit or smashed. That decibel figure was not measured here. At about £14.95 the box includes six LR44 cells and adhesive pads the listing also treats as warning stickers. Across 4.1 from 187 amazon.co.uk reviews, UK texts often call it loud when it does trip, easy to stick, and slim on the glass, including on a patio door and shed windows. The same sample has no sensitivity control: east-facing and south-facing glass trips in the sun, and other units need a hard hit or stay quiet when the window is only opened. One review says a bang from outside does nothing and only an inside tap works. Small LR44 cells are called hard to change once the unit is stuck on, and one unit fell apart so the batteries fell out. The title claims Secured by Design and Sold Secure. The listing gives no certificate number, so that claim is not confirmed here.
Pros
Cons
Best for: A hit on one pane, with cells already in the box, if you can keep it off sun-facing glass and you only need on and off.
Less suitable: Anyone who needs the sash opening itself to trip the alarm, or a dial to calm hot glass.
Specifications
Common questions
Are batteries included with the Defender 2-pack?
Yes. The listing says 6 LR44 alkaline batteries are required and included.
Does it detect an opened window or only a hit?
It is a vibration sensor. The bullets say a hit or smash triggers the 130 dB siren. Reviews split: some trip on a knock, others do not trip when the window is opened.
Is a weather rating listed?
No. The specification block has no IP code. The listing asks whether it is weatherproof and does not answer that in the spec fields.
The Flintronic D1-4630621 is a four-pack of slim vibration sensors at about £18.99, with a 130 dB claim that was not measured here. The bullets say turn it on, wait five seconds for a beep, then a trigger flashes a light and sounds for 30 seconds before it senses again, and they include three LR44 cells. amazon.co.uk lists 4.1 from 127 reviews. UK reviews in the sample call it loud and thin, and easy to stick, including on patio windows. Some units do not trip however hard the window is hit, others are called too sensitive, and reviewers who already owned an alarm wanted a warning sticker the bullets do not include. One battery cover came off when the activation flap was pulled. It can cover several panes with a timed siren if you test each puck and return a dead one. It is a poor fit for sun-facing glass if you need a sensitivity dial.
Pros
Cons
Best for: Covering several panes with a timed 30-second siren, if you can test each puck and return a dead one.
Less suitable: Sun-facing glass if you need a sensitivity dial, or a visible sticker the listing does not promise.
Specifications
Common questions
How does the Flintronic alarm arm?
The bullets say turn it on, wait 5 seconds for a beep, then it senses. A trigger sounds the siren and flashes a light for 30 seconds, then it senses again.
Are batteries included?
The bullets say 3 LR44 batteries are included. The specification block names alkaline batteries and does not repeat the count.
Does the listing include a warning sticker?
The bullets do not describe one. UK reviews ask for a visible alarm sticker like the older units they replaced.
The NICE Home ten-pack is a magnetic contact at about £14.99, about £1.50 a sensor before the cells, with a 95 dB claim when the two parts separate. That figure was not measured here. The box has 10 sensors and 10 sticks. The bullets say insert two AAA cells and that no battery is in the box. amazon.co.uk lists 4.0 from 870 reviews. In the UK reviews read for this comparison, sticky-back fitting is called quick, and some say the units were loud enough indoors, including one used as a fridge-door chime. The same sample is full of dead units, a single bleep then silence, or only a few working sensors in a pack of 10. Reviewers say the halves must sit flush, so standard or bevelled uPVC is a common return, and the sound often does not reach another floor. The unit price is the lowest in the set, and it still does not take the best-value badge.
Pros
Cons
Best for: Extra contacts on flush frames in the same room, if you already have AAA cells and can return a dead pack.
Less suitable: Bevelled uPVC, a bedroom on another floor, or a first alarm where you need most of the ten to work.
Specifications
Common questions
Are batteries in the NICE Home box?
No. The bullets say insert 2 AAA batteries and that there is no battery in the box.
Will the two halves fit a uPVC window?
UK reviews repeatedly say the parts must sit flush. Standard, bevelled or non-flush frames are a common reason for returns.
How many alarms are in the pack?
The bullets list 10 magnetic sensors and 10 magnetic sticks. The stated siren is 95 dB.
The Miangerrn Y-135 is a magnetic sensor the bullets sell as a Wi-Fi app alert with an 85 dB sound, at about £12.90 and 20 g. That decibel figure was not measured here. The specification field says Zigbee, the pack lines say both 2 packs and 1 item, and the battery is one non-standard lithium cell that is included. amazon.co.uk shows 3.0 from one UK review. That reviewer wanted a standalone unit and said it blends into a white uPVC frame, then said setup was difficult even for someone who works with alarm systems, because it needs its own app. The listing does not answer how far the magnet may sit, or whether it belongs on glass. One review cannot show whether the fault is the setup or the device. It is only a candidate if you are prepared to be an early reviewer and you want a separate app rather than a siren-only contact. It is a poor first window alarm, and a poor match for a household that already has a system this app will not join.
Pros
Cons
Best for: Only if you are prepared to be an early reviewer and you want a separate app rather than a siren-only contact.
Less suitable: A first window alarm, or a household that already has a system this app will not join.
Specifications
Common questions
Does the Miangerrn sensor use Wi-Fi or Zigbee?
The bullets say connect it to home Wi-Fi for app alerts. The sensor technology field says Zigbee. The listing does not resolve that.
How loud is the listed siren?
The specification block states 85 dB. It also lists 5 V and 5 W. That figure was not measured for this comparison.
What did the UK review say about setup?
The only UK review says setup was difficult and that the app does not join the reviewer's existing systems. The same review says it blends into a white uPVC frame.
Scores are out of 100 from the eight amazon.co.uk listings in this set, checked on 15 October 2026. There is no laboratory test. Decibel figures were not measured. Stars only count with the review count beside them. The top pick and the best value are separate: two listings tie on points, and only one takes each badge.
Amazon rating and review count
40%Star points rise with the average, and volume points rise with the listing count. A single review cannot outrank a sample of more than a thousand.
Sensor, controls and review evidence
30%A stated gap, a described trigger, cells the listing says are included, and whether UK reviews use the product as described. A protocol clash or a pack of dead units scores lower.
Price per stated unit
20%Shelf price in GBP divided by the pack the listing actually states. Cells that are not in the box, or a pack count that contradicts itself, reduce the score.
Listing clarity
10%Points come off for a Wi-Fi and Zigbee clash, a pack-count clash, dimensions that disagree, a missing size, or a battery line that does not match the bullets.
Name the event before you compare star ratings. A magnetic contact and a vibration puck answer different problems, and a stated decibel figure is a listing claim, not a measurement. Prices below are the eight amazon.co.uk shelf prices held on 15 October 2026. We did not run a laboratory test, and we do not claim that officers will attend because a siren sounds.
A window alarm in this set is a local noise maker, not a monitored burglar alarm. On amazon.co.uk it is usually a vibration puck stuck to the inside of the glass, or a two-piece magnetic contact that sounds when the window or door opens. People buy one as a deterrent and a way to wake the household. Police.uk and ProtectUK say an audible-only alarm is unlikely to bring officers unless there is other evidence of a crime. A Unique Reference Number needs a monitored system.
A magnetic contact sounds when the parts separate. It does not detect smashed glass while the sash stays shut. A vibration puck sits on one pane and does not cover the pane beside it. NPSA treats contacts, vibration detectors and break-glass sensors as different devices.
The listings state 85, 95, 100 or 130 dB. None of those figures was measured for this comparison. NICE Home reviewers often say the 95 dB pack is only heard in the same room. A siren at a shed may not be heard in the house.
Magnetic reviews here often fail on bevelled or non-flush uPVC. Defender reviews describe sun on east-facing and south-facing glass, and the listing has no sensitivity control. Reading Sold Secure into the Defender title is a separate mistake: the listing gives no certificate number.
The first split is the event. TECKNET, VOXON and NICE Home are magnetic contacts and trip when the parts separate. TECKNET states a gap of more than 2 cm and three volume levels. VOXON states 20 mm and no volume slider. Defender, Flintronic, WER and WOWSEA are vibration pucks for a hit on one pane. UK reviews of the magnetic packs often fail when the uPVC is bevelled or the two halves cannot sit flush. A puck does not watch the next pane.
VOXON, Defender, Flintronic and WER say LR44 cells are included. NICE Home says two AAA cells are not in the box, which is why the low unit price does not win the value badge. TECKNET and WOWSEA do not clearly say the cells are included. Stated levels are 85, 95, 100 or 130 dB and were not measured. Keep the police response separate. Police.uk and ProtectUK say an audible-only activation is unlikely to bring officers unless something else supports a genuine alarm.
Three typical situations, each with a recommendation from this comparison.
You want a noise when a window or door opens, and you want to turn the volume down. TECKNET is a three-pack at about £13.99, rated 4.6 from 1,479 reviews, with off, chime, alarm and three volume levels. Lock the window as well.
You need a trip when a door opens, and you want the cells in the box. VOXON is four sensors at about £12.74, rated 4.4 from 1,826 reviews. UK reviews include a child who can reach a latch, and a siren heard from another floor. There is no volume slider.
You are fitting a shed or one pane, and you can accept that a siren at the bottom of the garden may go unheard. WER is a two-pack vibration puck at about £15.97, rated 4.4 from 236 reviews, with three LR44 cells included. Heavy rain has tripped at least one unit.
For a magnetic contact on a flat frame, when you want the siren turned down, the top pick is the TECKNET TK-WA801 three-pack at about £13.99, rated 4.6 from 1,479 reviews. It ties on points with VOXON and takes the badge on the 4.6 average and three volume levels. The listing does not say the cells are in the box, so it is not the best value. The best value is the VOXON four-pack at about £12.74, about £3.19 a sensor, rated 4.4 from 1,826 reviews, with four LR44 cells stated in the bullets. The NICE Home ten-pack is cheaper per sensor and does not take that badge: sampled reviews are dominated by dead units, and the AAA cells are extra. Stated decibel figures were not measured, and none of these listings is a monitored alarm with a police Unique Reference Number.
VOXON magnetic window alarm, 4-pack
Four sensors at about £12.74 with four LR44 cells in the bullets, 4.4 from 1,826 reviews.
Editorial
Products Compared publishes British-English buying guides based on amazon.co.uk listings and public UK sources. We do not run a lab and we do not invent test scores.
Guides on what to look for, how to use a product, and common mistakes.
Public UK sources and the amazon.co.uk listings in this comparison. Listings checked 15 October 2026.
Expert source (DIY & tools): Charlie White (Charlie DIYte) (external profile) – public expert commentary used as a research source, not as a contributor to our pages.
This page contains affiliate links to amazon.co.uk (tag pcuk26-21). If you buy through them, we may earn a commission at no extra cost to you. Prices, stars and review counts are from the amazon.co.uk listings checked on 15 October 2026. We did not run a laboratory test.
