**This product has been discontinued by the Manufacture, Eterna. The closest alternative is the Hi-Spec Mains Heat Detector with 9V Battery Backup - Available Here** This heat detector by Eterna is ideal for rooms where steam or smoke is a usual occurrence. Instead it will detect rising temperatures and is connected to the UK mains for power so you never need to change the battery. Although a back-up is supplied. Features: Plug in power harness: easy and quick connections Up to 40 mixed units interconnectable - Both Heat and Smoke Alarms Twist and lock mounting base plate - Can be used with the Eterna SDBASE Fixed temperature operation Alarm trigger and mains healthy LED Hush feature Battery back up included Low battery signal Specification Sheet/Instruction Manual