This one is really nice - is a combination of smoke alarm and Carbon Monoxide alarm. You may recognize the Kidde name. The Kidde Corporation is famous for their high quality fire extinguishers. Because it's battery-operated, you won't have to worry about being warned if the power goes out. There is a low battery indicator so you can make sure it has the power it needs.
Comments from the website/manufacturer:
Manufacturer: Kidde Safety. Sold Individually. Battery-Powered Night Hawk Combination Smoke/CO Alarm with Voice & Alarm Warning Two-alarm system features a loud volume voice warning: "Fire, Fire!" or "Warning! Carbon Monoxide!" Low-battery indicators included.
See this item here:
Battery Powered Night Hawk® Combination Smoke/CO Alarm with Voice/Alarm Warning. Sold Individually