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X-Sense SBS50 base station or a standalone alarm

Updated: 21 October 2026

The SD11 is about £11.99 and the FS31 kit is about £63.99. The X-Sense SBS50 base station is the piece that decides which of those prices is a finished system. A standalone head sounds on its own ceiling. A head that needs the hub stays quiet as a whole-home siren until that base is in the house, on 2.4 GHz, with the adapter powered. A phone push is not that siren. Listings were captured on 19 October 2026, with no lab test. A qualifying purchase can earn us a commission at no extra cost to you. Prices sit on the [X-Sense smoke detector comparison](/hub/fire-protection/x-sense-smoke-detector). Nation rules stay on the [buying guide](/hub/fire-protection/x-sense-smoke-detector/sub/x-sense-smoke-detector-buying-guide).

The SD11 is about £11.99 and the FS31 kit is about £63.99. The X-Sense SBS50 base station is the piece that decides which of those prices is a finished system. A standalone head sounds on its own ceiling.

Our top picks

X-Sense X-Sense SD11

Best overall

X-Sense X-Sense SD11
8.6/10about £11.99
View offer
X-Sense X-Sense XS0G-SN

Best value

X-Sense X-Sense XS0G-SN
8.4/10about £20.39
View offer
X-Sense X-Sense FS31

Alternative

X-Sense X-Sense FS31
8.2/10about £63.99
View offer
On this page
  1. 1.When a standalone alarm is enough
  2. 2.What the SBS50 actually adds
  3. 3.Listings that still need a separate base
  4. 4.Link+ and direct Wi-Fi are not the hub

When a standalone alarm is enough

Choose a standalone when one or two ceilings need a local horn and you do not want an account. The SD11 at about £11.99, 4.5 from 7,170 reviews, has a sealed cell and no app. The quality warranty is five years, and UK reviews include sealed cells that died well inside ten years. The XS0G-SN two-pack at about £20.39 does not sound together. It is the best value for two separate rooms, and the wrong pack if those ceilings must answer each other. Combination models are on the smoke and carbon monoxide page. A standalone SD11 does not meet a Scottish interlinked pattern.

What the SBS50 actually adds

The manufacturer's SBS50 page, cited for this set, describes a hub on 100–240 V, 2.4 GHz only, up to 50 devices, and 100 dB. A BS 1363 plug is not confirmed on the UK listings, so check the adapter rather than assuming a UK 13 A plug. The FS31 at about £63.99 puts three XS01-M alarms, three CR123A cells, the SBS50, an adapter and a cable in one box. The listing claims 85 dB on each head and 100 dB on the base, and says 5 GHz is not supported. Cell life in years is not stated, and there is no heat alarm.
X-Sense X-Sense SD11

Testsieger

X-Sense X-Sense SD11
8.6/10about £11.99
View offer

Listings that still need a separate base

Several titles read like a finished Wi-Fi alarm and then say the base is required. The XS01-M at about £19.54, 4.7 from 683 reviews, stays an accessory until the hub is in the same order. About £19.54 is not a system. The XS0B-MR three-pack at about £59.99 and the XP0A-MR at about £35.99 require the SBS50 and do not include it. Buy them only as extra heads for a hub you already own. Fitting is on how to fit an X-Sense smoke alarm.

Common questions

What does the SBS50 base station do?
It is the hub that lets compatible heads share an alarm and an app. The cited product page gives 100–240 V, 2.4 GHz only, up to 50 devices and 100 dB. In the FS31 box it arrives with three XS01-M heads, and the listing says the app can test, silence and share the system with up to 12 people. 5 GHz is not supported. A phone notification without this base, on a direct Wi-Fi head, does not make the other ceilings sound.
Can the XS01-M work without the base?
The head can sit on a ceiling, and the listing does not describe it as a standalone system. It says the SBS50 is required, and the base is not in the about £19.54 box. Without that hub you do not get the app test, the shared siren or the 2.4 GHz link the listing is selling. If you wanted a single optical alarm with no account, the XS01 at about £16.99 states that it is not compatible with the base, which is a different product.
Is the FS31 worth it over three SD11 alarms?
Three SD11 alarms are about £36 and three separate horns. The FS31 at about £63.99 adds the SBS50, so one test can be meant to raise every head, plus a 100 dB base and an app. The review file is 198, not 7,170, and the cells are replaceable CR123A. Pay the difference when linked sound is the requirement. Stay with the SD11 when each ceiling only needs to protect itself.
Does Wi-Fi replace interlink on X-Sense?
No. Wi-Fi on these products is 2.4 GHz, and radio interlink is a separate behaviour. The XS0B-iR and the SC07-WX use Wi-Fi and the listings say they do not interlink. Scottish guidance does not treat Wi-Fi as the thing that satisfies interlink. A push notification to a phone in another room is not an 85 dB horn on the landing. If the brief is that all heads sound, read the box for an SBS50 or a Link+ claim, then test it.
Which heads are sold as accessories only?
The XS01-M at about £19.54, the XP0A-MR at about £35.99 and the XS0B-MR three-pack at about £59.99 all require an SBS50 that is not in the carton. The FS31 at about £63.99 and the SD11-MR31 at about £64.59 are the two listings in this set that put the base in the box. Buying an accessory head first, then discovering the hub, is the expensive version of the same system. Order the kit, or own the base already.

Related pages

Best X-Sense smoke detector

X-sense smoke detector

X-Sense smoke alarm buying guide: nation and family

How to fit an X-Sense smoke alarm and test it monthly

X-Sense smoke and carbon monoxide alarm: three heads

Sources

Public UK sources from the research digest, last checked on 19 October 2026. Prices, stars, and review counts are the amazon.co.uk lines captured that day.

  1. GOV.UK — Smoke and carbon monoxide alarms, landlord booklet (retrieved 19 October 2026)
  2. Scottish Government — fire and smoke alarms, where and what to buy (retrieved 19 October 2026)
  3. Scottish Fire and Rescue Service — smoke and heat alarms (retrieved 19 October 2026)
  4. legislation.gov.uk — Wales, WSI 2022/6 (retrieved 19 October 2026)
  5. Northern Ireland Department for Communities — smoke, heat and carbon monoxide alarms (retrieved 19 October 2026)
  6. London Fire Brigade — smoke alarms and heat alarms (retrieved 19 October 2026)
  7. Fire Kills — detect (retrieved 19 October 2026)
  8. X-Sense SD11 user manual (retrieved 19 October 2026)