Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Does the job

This bottle warmer does the trick. After reading other reviews it does have an on and off switch, they just never looked for it. If your bottle is floating then it's obvious you have too much water in it. As for the timing of the warmer. You do have to guess on how long to leave it in. But after you do it for a while you can estimate how long it should take. I only overheated once or twice and for reasons. I think this bottle warmer is great. It warms the bottle evenly.