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Window alarm: which sensor to buy

Updated: 16 October 2026

You are looking at a ground-floor uPVC window, or a door a child can reach, and a listing that looks like a burglar alarm. A window alarm in this amazon.co.uk set is a peel-and-stick siren. It does not call the police. By the end you should know which event you are buying for, whether the frame can hold the parts, and whether the cells are in the box. The eight-row table, checked on 15 October 2026, is the [window alarm comparison](/hub/burglar-protection/window-alarm). This page is from the Products Compared editorial team. We did not measure the decibel claims. A qualifying purchase can earn a commission at no extra cost to you.

You are looking at a ground-floor uPVC window, or a door a child can reach, and a listing that looks like a burglar alarm. A window alarm in this amazon.co.uk set is a peel-and-stick siren. It does not call the police.

Our top picks

TECKNET TECKNET window and door alarm, 3-pack

Best overall

TECKNET TECKNET window and door alarm, 3-pack
8.6/10about £13.99
View offer
VOXON VOXON magnetic window alarm, 4-pack

Preis-Tipp

VOXON VOXON magnetic window alarm, 4-pack
8.6/10about £12.74
View offer
WER WER Doberman slim window alarm, 2-pack

Alternative

WER WER Doberman slim window alarm, 2-pack
6.8/10about £15.97
View offer
On this page
  1. 1.What a window alarm on amazon.co.uk actually does
  2. 2.Match the sensor to the event
  3. 3.Frame, sound, and batteries
  4. 4.What the police will not do

What a window alarm on amazon.co.uk actually does

These units stick to glass or a frame and make a noise in the house. Contacts trip when two magnetic parts move apart. Vibration pucks trip when that pane is hit. Neither phones a monitoring centre, and neither is a room-listening glass-break sensor. The National Protective Security Authority treats those three as different devices. They are not a graded intruder system. The Defender ultra-slim title claims Secured by Design and Sold Secure. Register pages checked for this set did not list this ASIN, so that line is not police attendance. Named conditional picks are on the best window alarm page.

Match the sensor to the event

A magnetic window alarm reports an opening. TECKNET’s TK-WA801 keeps sounding beyond 2 cm, with three volume levels, at about £13.99 for three and 4.6 from 1,479 reviews. The cells are not stated as included. VOXON, about £12.74 for four, starts beyond 20 mm, includes four LR44 cells, and has no volume slider. NICE Home is about £14.99 for ten. Skip Miangerrn: Wi-Fi in the bullets, Zigbee in the specification, and 3.0 from one UK review. A vibration window alarm reports a shock on one pane. Defender, Flintronic and WER state LR44 cells in the box. WOWSEA does not settle a pack of four or one. One puck does not cover the pane beside it. The mechanism page is vibration alarm versus contact.
TECKNET TECKNET window and door alarm, 3-pack

Testsieger

TECKNET TECKNET window and door alarm, 3-pack
8.6/10about £13.99
View offer

Frame, sound, and batteries

The right sensor still fails on the wrong frame. NICE Home and TECKNET reviews say the halves must sit flush, and a bevelled uPVC edge is a common return. VOXON will not see a door already further apart than 20 mm, and a left-hand door is fitted upside down. Read the battery line before the shelf price. LR44 cells are stated for Defender, Flintronic, WER and VOXON. NICE Home needs two AAA cells that are not in the box. TECKNET and WOWSEA do not clearly say the cells are included. No listing prints an IP rating.

What the police will not do

Police.uk says officers typically respond when a police-compliant monitoring company asks. ProtectUK says police will not attend an audible-only activation unless something else supports a genuine alarm. If you can see a crime, call 999. Do not put 999 in an auto-dialler. A unique reference number belongs to a monitored installation, specified against PD 6662:2017 and BS 8243:2021 since June 2019. That is an installer, not these ASINs. nidirect says lock first, with BS 7950 for windows and PAS 24 for doors. Hire a professional for that route, a failed lock, or a drill into the sealed glazing.

Common questions

Does a window alarm call the police?
No. These units are audible only. Police.uk says officers typically respond when a police-compliant monitoring company asks, and ProtectUK says an audible-only activation is not attended unless something else supports a genuine alarm. If you can see a crime, call 999. A repeating siren with no other sign of a break-in is a council noise issue.
Should I buy a magnetic contact or a vibration puck?
Buy a contact to hear a door or sash open on a flat frame. Buy a puck to hear a hit on one pane, and stick one unit to that pane only. A contact stays quiet if the glass breaks and the sash never moves. A puck can stay quiet if the window opens without a shock. The decibel claim does not make that choice.
Will a contact fit a bevelled uPVC frame?
Often it will not. TECKNET and NICE Home reviews say rounded or non-flush frames stop the halves meeting. VOXON needs the parts within its 20 mm trip, so a gap that is already wider never looks shut. Forcing pads onto a curve is a return. A puck avoids the join and still covers only the pane it is stuck to.
Are the batteries in the box?
Defender, Flintronic, WER and VOXON say LR44 cells are included. Miangerrn includes one non-standard cell. NICE Home needs two AAA per sensor and says they are not in the box. TECKNET and WOWSEA do not clearly say the cells are included, so a silent unit may have arrived empty. Check that line before you treat the shelf price as the whole cost.
Can I trust the decibel number?
Treat it as a claim. The listings print 85, 95, 100 or 130 dB, and this comparison did not measure them. NICE Home reviews often keep the sound in the same room. VOXON reviews include another floor, with no volume control. A higher number on the title is not a test result.
When do I need an installer instead of a peel-and-stick unit?
When you want a police unique reference number, an insurer-specified grade, or a repair to a failed lock or frame. Systems that want the police route are specified against PD 6662:2017 and BS 8243:2021, which these pucks are not. Stop as well if the fit needs a drill into the sealed unit. A stick-on siren is a household noise after the window is already locked.

Related pages

How to fit a window alarm

Window alarm false alarms

Window alarms

Best window alarm for a glass hit or a door opening

Vibration window alarm vs magnetic contact, explained

Sources

Public UK sources and the amazon.co.uk listings in this comparison. Listings checked 15 October 2026.

  1. Police.uk: keep burglars out of your property (retrieved 15 October 2026)
  2. ProtectUK: alarms and CCTV (retrieved 15 October 2026)
  3. nidirect: securing doors and windows (retrieved 15 October 2026)
  4. GOV.UK: how councils deal with noise complaints (retrieved 15 October 2026)
  5. Clean Neighbourhoods and Environment Act 2005, alarm powers (retrieved 15 October 2026)
  6. NSI: intruder alarm systems (retrieved 15 October 2026)
  7. NPSA: intrusion detection (retrieved 15 October 2026)
  8. Avon and Somerset Police: burglar alarms (retrieved 15 October 2026)