The Ei156TLH is an optical smoke alarm that runs on 230V mains power. The Ei156TLH has a built in tamper proof rechargeable lithium cells that act as a better back up incase the mains power was to fail. The reliable back up battery has a life of 10 years which will out live the smoke alarm itself. Also the alarm is very suitable for DIY instillation without any need for an electrician.
This smoke alarm also has the function to interconnect with other Ei Proffesional mains powered smoke and heat alarms. The Ei156LTH is proven to be more responsive to slow smouldering fires and to detect them earlier than other products could.