Instruct: Classify a review as either positive or negative.
Query: Keeps water from freezing

Keeps water from freezing, works fine. The power cord is covered with spiral metal (sort of like a stretched-out slinky) to keep dogs from chewing on the cord and getting electrocuted. The spiral metal is not very thick or strong, however, so if your dog is an aggressive chewer, it may get through the covering. If your dog doesn't chew or gives up easily, no problem.