It works well so far, got the 50W version for a 5 gallon tank, seems to maintain temperature well, and I like the look of his one. One thing, there is a sticker on the top that says something 50W on one side and I forget the other side. You can take that off pretty easily, and it exposes the guts a little, a chip and some red wires. I would rather look at the guts that the tacky sticker, and also it's probably not best for the fish to have sticker adhesive in the tank.Oh, and totally submerge, dSee full review