Hi, that exoterra heat mat will be fine, but make sure you have a thermostat or rheostat. Back when I kept my bps in tanks, I used the exoterra rainforest heat mat, which is only 8 watts. They heated up to 90-95 easily, and sometimes on a really hot day in the summer they would go over 100. So I imagine the 16 watt desert heat mat would easily hit 120 on a summer day if unregulated. So I'd definately invest in a lamp dimmer if anything. I'm not trying to shun you away from the desert heat mat, seeing as you already bought it. It probably does have the advantage though, in the winter, of maintaining a nice 90-95. The rainforest ones hit 80-85 at max and have to be helped out with a heat lamp, so I think you probably made the right choice getting the desert one, but DEFINATELY use a rheostat.

Hope that helps.