I liked the chew-proof cord, the waterproof covering, and the cat-level temperature. The pad fits in an outdoor dog kennel that's covered with a duvet and rug and occupied by 2 feral cats. I suppose the fact that they spend all day sleeping in the kennel should be evidence that at least it isn't doing any harm. I stuck my hand in the kennel just after they had exited and the pad was warm. Couldn't tell if that was from electricity or the cats' natural body heat.So far, so good.