I went to radio shack and bought a 2" micro fan. I already had a 12v adapter. It was an old one used to charge a flashlight. I cut the ending of the fan wire and the ending off the adapter. Wired them together,put caps on the bare wire and plugged it in. Works great. And it is the perfect size for the 2" opening. Temp dropped from 82* to 80* in an hr. Now to get the fan(cooler) and the heater to keep a constant temp. All for less than $18.00!! Im a happy camper