You'll want a CHE (ceramic heat emitter) which is similar, but it only puts off heat and not light. Using a heat lamp can disturb their waking/sleeping cycles because of the light it puts off. You'll need a thermostat as well, which is used to control the CHE and turn it on and off to keep the cage in the right temperature range that you set it to. Details about the equipment are in this thread:
viewtopic.php?f=8&t=4579