I've got an AP cage. It's got the place on the bottom for their recommended placement of the probe/flexwatt. I'm not sure if the flexwatt or an uth would be better, or if it makes much difference at all. I read somewhere that the flexwatt sags a little, and is better to use if you have cages/tubs to stack. I will be getting a herpstat 2 to hook up to whatever I end up getting. Opinions? TIA