37242. The Abus RWM150 is an optical smoke alarm fitted with a non replaceable lithium 10 year battery. It is recommended for bedrooms, living rooms, children's rooms and corridors up to 40 square metres in size, has a loud 85 decibel alarm and is tested according to DIN EN 14604.. Loud 85 dB alarm. Built in non replaceable 3V Lithium battery (10 Year). Room detection range: up to 40 square metres. Hush function for 9 minutes