Gentex GN-303 Photoelectric Smoke Alarm Horn frequency 3150 Hz (Nominal) Nominal 2.5% sensitivity Push button test feature On-site maintenance washing program Includes battery drawer on side of unit to allow for battery replacement without removing unit from wall or ceiling Includes low or missing battery indicator Quick-disconnect wiring harness Sure-Lock&trade; locking pin to detour alarm tampering Dust-Cover included to keep units dust free until occupancy Temporal 3 evacuation sounding device Pulsing LED sensing chamber Easy Wash&