The Kidde Front-Loading Smoke and Carbon Monoxide alarm (part # 21007624) offers protection from two hazards – fire and CO – in one unit. Sold under the FireX brand this AC-wire with battery backup alarm emits a beeping tone followed by a voice warning that clearly announces the danger by saying “Fire! Fire!” or “Warning! Carbon Monoxide!”. The uniquely designed frontloading battery compartment makes battery replacement quick and easy and ensures proper installation. Manufactured with photoelectric sensors for detecting smoke and fire this alarm also includes the world’s most accurate CO sensing technology based on claims by major manufacturers. 10-Year Life: “If your CO alarm was manufactured prior to 2013 it does not have a 10 year life.