This 2nd generation battery smoke carbon monoxide alarm uses electrochemical sensors to effectively detect dangerous carbon monoxide fumes and alert you to their release. Recommended for use in any indoor room. 5 year Lithium Battery powered Full self test and Low battery warning signal Easy to install with fixings provided Features and Benefits Nest Protect has been completely redesigned for it's 2nd generation launch. It has an industrial grade smoke sensor can be silenced from your phone tests itself automatically and lasts for up to 10 years. It also tells you what's wrong and can even alert your phone. Nest Protect alerts your phone when something s wrong when you are not home. In the unfortunate instance when something isn t quite right the Nest Protect speaks up to tell you if there is smoke or carbon monoxide and where the danger is. It is also the first alarm you can silence from your phone. Simply download the Nest app to your Smartphone to gain full control of the situation. Split Spectrum Sensor that detects both fast and slow burning fires Sends alerts on your phone even when you are away The first alarm that you can silence from your phone It speaks up to tell you what's wrong and where the problem is Keeps you safe and sound for up to 10 years. The longest time allowed by law.