This is a dangerously unresponsive smoke alarm and a Which? Don’t Buy. It failed three of our four smoke detection tests and the consequences of this happening in your home could be fatal. So, don’t be tempted by the low price you might see this alarm being listed for. It’s listed as an unbranded alarm on online marketplace Wish with the model number CS01 and it’s one to avoid. Wish told us: ‘We take product safety very seriously, and require that our merchants sell products that comply with local laws and regulations, as stated in our Wish’s Merchant Terms of Service and Wish Policies. The listing reported by Which? has already been removed. We have also carried out a sweep across our platform to try to remove identical or similar listings. Should any additional listings be identified, they will be promptly removed and any affected purchasers and merchants will be notified immediately.’

UnbrandedCS01

Smoke alarm
Battery only
Optical smoke alarm

£18Typical price

Test score

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KEY TEST RESULTS
Wood fires
Cotton fires
Sound output

Sept 2022Last checked by Which?
Sept 2022First reviewed by Which?

The overall Which? test score is made up of the following star ratings, all determined by our rigorous lab tests.

How we test smoke alarms and heat alarms

27 Feb 2024

Wood fires

How we test wood fires

We measure the amount and thickness of wood smoke from a smouldering fire that is required to trigger the alarm. This test isn't carried out for heat alarms, which are tested to a different programme. Only applicable to smoke alarms.

Wood fires

How we test wood fires

Cotton fires

How we test cotton fires

We measure the amount and thickness of cotton smoke from a smouldering fire that is required to trigger the alarm. This test isn't carried out for heat alarms, which are tested to a different programme. Only applicable to smoke alarms.

Cotton fires

How we test cotton fires

Plastics fires

How we test plastics fires

We measure the amount and thickness of smoke from a plastics fire that is required to trigger the alarm. This test isn't carried out for heat alarms, which are tested to a different programme. Only applicable to smoke alarms.

Plastics fires

How we test plastics fires

Solvent fires

How we test solvent fires

We measure the amount and thickness of smoke from a solvents fire that's required to trigger the alarm. This test isn't carried out for heat alarms, which are tested to a different programme. Only applicable to smoke alarms.

Solvent fires

How we test solvent fires

Sound output

How we test sound output

Sound output is based on decibel levels, measured in a fully soundproofed chamber. Three stars or above are louder than 85dB – the equivalent of a lawn mower. Ones rated two stars or below should probably be avoided by those with poor hearing. This test isn't carried out for heat alarms, which are tested to a different programme. Only applicable to smoke alarms.

Ease of use

How we test ease of use

Ease of use includes clarity of instructions including installation and maintenance, how simple it is to insert and replace the battery, use the hush button and any interconnectivity features. This test isn't carried out for heat alarms, which are tested to a different programme. Only applicable to smoke alarms.

General
Type	Smoke alarm
Power source	Battery only
Technology	Optical smoke alarm
10-year battery	No
Wood fire response time (Smoke alarms only)
Cotton fire response time (Smoke alarms only)
Plastics fire response time (Smoke alarms only)
Solvent fire response time (Smoke alarms only)

Features
Light	No
Hush button	Yes

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How to place and maintain smoke alarms
Buying a smoke alarm isn't enough when it comes to fire safety – you need to buy the right one for your home and position it correctly. Find out how.
How we test smoke alarms and heat alarms
To uncover the Best Buy smoke alarms that you can trust, we put every smoke alarm we review to the test against four different types of fire. And for heat alarms - which detect rapid temperature rises - we run five heat detection tests to check how well they work.
Best smoke alarms
Which smoke alarm should you buy - ionisation, optical or heat alarm? Find out how to choose the best smoke alarm for your home.

All smoke alarm advice

UnbrandedCS01

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pros

cons

How we test smoke alarms and heat alarms

Wood fires

Wood fires

Cotton fires

Cotton fires

Plastics fires

Plastics fires

Solvent fires

Solvent fires

Sound output

Ease of use

How this product's score compares with other smoke alarms we've tested

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FireAngel

Nest

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UnbrandedCS01

pros

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Test results

Specifications

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