Essentially these are the pads you ll find in almost every discount store, such as Walmart, KMart, and Venture. They re designed for humans for the relief of minor aches and pains. There are several different models with a variety of brand names. Most provide 50 watts of heating on the high setting. These pads are great because they re cheap, heat evenly, provide a large surface area, and the temperature can be adjusted via the switch.
Larger enclosures can use more than one pad.
These pads are claimed to be waterproof, and they do indeed seem to be tightly sealed. Most users place them under the herp enclosures, though I see no reason they couldn t be used under sand or similar substrate. These pads do get very hot though, so be sure your herp isn t exposed directly to the pad. I use these pads exclusively to breed Leopard Geckos and they work fantastic. I use large 65 quart Rubbermaid containers, and one heating pad per enclosure.