From what I have read you need to stay away from a rheostat, and get a thermostat. I have two UTH's and two thermostats. The UTH's (ZooMed) were $45.00 each. The Thermostats are Zilla Brand I believe, and they were $49.00. I bought these thermostats and UTH's at Petco before I joind this site, and although they work very well for me I am worried I should have ordered some "better" models. I have a temp-Gun to double check my heat, and all is well. I keep a log and my Daughter documents her feeding, shedding, weight, humidity & temps (trying to teach my daughter responsibility in caretaking).