Exo Terra Reptile Heat Mat, 18-watt

This 4 watt heater is all the heat my leopard gecko needs in a large cage to have one side a bit over 85* F. We have a glass cage with tile in half and terrarium carpet in half. The tile side when covered with a hide spot can get up to 90* according to my instant temp gauge, but is usually more like 80-85. The carpet side a little cooler, more like 75-80*. So on the tile part over the heater we have a jar filled with moss for his shedding area. The mason jar is about the size of the heater and just big enough for the leopard gecko to turn around. The heater is smaller than the packaging. (About half the size of the cardboard). It is important to measure the temperature of these underground heaters weekly, because things can change. You would think your pet would get off if it's too hot, but like a frog in hot water, he doesn't realize it's too hot until he's burnt and still won't get off. My lizard's feet were burnt on his last underground heater so the vet said to only use overhead heating. But he was avoiding the cold mason jar despite needing it, so we have the 4 watt heater under there and the basking light opposite corner. In between the two is 75*. (The cage is about 3 feet wide.)