* Unique cover Button Design, Easy to test regularly * Fast Response, Alarm immediately when detected smoke * High Audibility Level over 85dB/3m, enough to wake you up when the danger comes * Unique Dust-Proof Design,Prevent false alarm * Ultra thin, Exquisite and Modern Appearance * Battery type can be customized :Carbon zinc(1 year),alkaline(3 years), lithium(5 years and 10 years). * EN14604：2005 certified product standards