Here is a nice digital unit. They are running a sale right now too.
http://www.petmountain.com/product/r...ermometer.html

Or you could go to Walmart and get an Accurite and do this.
http://www.ball-pythons.net/forums/s...ad.php?t=92057

Oh yeah, almost forgot, theses are really good enclosures and are very secure too.
http://www.zilla-rules.com/products/critter-cages.htm