... ,wireless alarm system )1. Form by DC Operated Wireless Smoke/heat/Carbon Monoxide/Ionization Alarm ( VST-WS588I, VST-WS588IH, VST-WH588I , VST-WC588I, VST-WIS588I, and ... , SAI Global approved with EN14604 Working Frequency433MHz /868M HzPower Source9 volt BatteryAlarm Sound Level85 decibels at 3 metersEmission distance>60m Wireless smoke alarm system