Hush Button(mute function).Test by hand,Low battery warning. Low standby current,Auto reset,ASIC adopted Anti-light, mothproof,Strong adaptability for circumstance SMT design, high stability Operating voltage: 110VAC or 220VAC Backup Battery: 9V battery Static current: ≤10uA Alarm current: ≤15mA Alarm indication: LED flash Sound level: ≥85dB/3 meters Operating temperature:40℉ to 100℉(4℃ to 38℃) Operating humidity: 5%-95% RH Sensitivity:2.06%/ft Detecting area: 20 square meters Alarm output: sound and flash alarm Size: 128 x 38mm deep cascade connection 40pcs at most. Execute criterion: EN14604,UL217