TES Lighting - The Ei141RC Ionisation Smoke Alarm is a mains powered alarm with a 9V Alkaline battery back-up and contains a proven long life Ionisation smoke chamber. Different alarms sensors work
Aico EI146E Optical Smoke Detector Mains Powered | Downlights Direct
Ei141RC Ionisation Smoke Alarm | Aico
Aico 230v mains powered smoke alarm at UK Electrical Supplies