I have a new just bought 2 weeks ago Nest Protect(co/smoke detector) wired version if you have American Family for your home insurance, You get a discount for having one of these in your home.

I had a Battery version for a year I wanted to move to a old on the ceiling smoke detector location which the backplate of it did not fit the holes of the holder. I had to get the wired version to get the backplate which had the hole locations on the backplate . So bought the wired version and told Nest customer service I broke the backplate and like to buy one If I could, They sent it out free Fed ex had it in 2 or 3 days with the special flathead screws

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