However one downside is that they also can't be turned off (by design) and the hush function on the ones I've tried (two models, both from Kidde) has been defective. No matter if I repeatedly press it, hold it, it doesn't care. It says hush mode then immediately blast again.
I destroyed the first one because it was night time and I have neighbors. Now I put them in the freezer. Next time I'll get another brand!