They look like this - they are used for watching weather conditions.

http://www.chaneyinstrument.com/pgs/inwea.htm

You can get an alife themostat for around 30 bucks. You really need something to control temps. I would only use a dimmer type themostat IF the temps in the room never fluctuate and are constant.

http://lllreptile.com/store/catalog/...at-with-probe/