120-volt AC/DC wired-in smoke, carbon monoxide, and natural gas detector with ionization sensor and 9-volt battery backup. Microprocessor virtually eliminates nuisance alarms. Product end-of-service life warning. Loud 85 dB alarm. Test/reset button. Quick Draw® battery drawer. 4 LED’s indicate power, smoke, carbon monoxide and natural gas. Interconnectable up to 24 compatible devices. Tamper resistant locking feature. Battery activation pull tab. 9-volt super heavy-duty battery included. Listed to UL2034 Standard. Size 5.75” x 5.75” x 1.75”.