The PSA Lifesaver 6800 model is a mains powered, 9V battery backed smoke alarm. The alarm uses photoelectric technology and is designed to be surface mounted on the ceiling or wall. When used with the 6000WB (wireless RF interlink baseplate), the alarm offers wireless interlinking capabilities as well as remote test/hush functionality with 6000THL (wireless smoke alarm controller)Features 6 x Smoke Alarms VALUE PACK ideal for installers. Less Packaging, Less Waste, More Savings! New advance sensor technology and intelligence to reduce sensitive activations. Anti-static sensor to repel dust particles. Easy installation & maintenance with QUICK SLIDE base. Mains powered, surface mount smoke alarm 240V AC with 9V battery backup (Duracell battery supplied) Photoelectric sensing technology Increased resilience to electrical interferences and dirty power. Chamber monitoring feature and first to alarm memory Switch-mode power supply uses less power and safer operation.