The Gentex Firebyrd™ series is a photoelectric single- or multiple-station smoke alarm. The series virtually eliminate nuisance alarms. The GN-20 series is a 120-volt AC hard-wired smoke alarm, and the GN-300 series is a 120-volt AC hard-wired smoke alarm with a 9-volt DC alkaline battery backup. The GN-300 series includes a battery drawer on the side of the unit. The GN-200 and GN-300 series produces an 85 db continuous tone while the GN-203 and GN-303 produce an 85 db temporal three evacuation tone.