I purchased a Plug In CO Alarm With Battery Backup from Sears. I am happy with my purchase. Alarm is loud and accurate. No false alarms that can be annoying.
Less than one month of usage and the unit is chirping malfunction code. very disappointed
I put the enclosed battery on. One day later, the alert indicates the battery needs to be replaced. The DMM measure confirmed it. I have to buy a 9V battery.
NEVER DELIVERED. Has been ordered by me twice, and by Sears help chat twice. 4 times the ordered has been screwed up. Sears is the worst. Now it's been cancelled due to lack of the item in stock. Why did the chat person order me an item that was out of stock.
These were recommended by our HVAC service technician and the plug in with the battery backup works great.