One other thing that's not been mentioned...Rancos are the on/off t-stats which means they *CLICK* on and off....if you're like me and sleep in the same room as your reptiles and you're trying to sleep at night and you hear CLICK......CLICK......CLICK......it gets rather annoying. The proportional Helix/Herpstat t-stats control the heat electronically, so you never hear power being turned on and off....