FIRST ALERT Carbon Monoxide Alarm | BRK CO250 Battery Operated Carbon Monoxide Detector With 9-Volt Battery & Two Silence Features

I bought this because I needed only a CO detector, which is surprisingly hard to find, and I wanted one that fit in the location where I already had one installed. The detector arrived in a non First Alert branded box, so I thought at first, this was a little Amazon bait and switchero. Upon closer inspection, however, this IS a First Alert product. If you look at the online product listing, it indicates that the device is manufactured by BRK (which is what the box showed.)Anyway, the screw holes on the detector fit the existing locations of my old Kidde detector, which is what was important to me.