It really is dependant on things like room temps, substrate enclosure type and on and on. I usually set mine so it delivers 90ºF I really don't like to have the heating element set hotter than 94 no matter where it is. I also (with out snakes of course) do a 'run away test' I'll plug the unit in directly and leave it for a few hours to find the absolute max temp. I try to keep mine no hotter than 100ºF in the worse case snakes can tolerate that temp for a brief period of time. Hopefully that never happens ...