I use a standard heating pad to keep my Dubia roach colony warm. It won't melt through even on the highest setting. It can get it hot enough that it could be uncomfortable inside the tub. On low it heats the inside to about 95* (measured with temp probe about 1/2 inch off the bottom of the tub). I placed a thin towel between the base and pad and it dropped it down to 90-92*.