... /220VAC power supply,9V back-up battery,85dB/3m,Wireless interconnection,meets EN14604,UL217 Test by hand,Low battery ... /220V ACBackup Battery: 9V battery Static current: ≤10uA Alarm current: ≤15mA Alarm indication: LED flash Sound level: ≥85dB/3 meters ... Detecting area: 20 square meters Alarm output: sound and flash alarm Size: 128 x 38mm deep Wireless interconnectionExecute criterion: EN14604,UL217