"bulb" isn't exactly the right word and I shouldn't have used it, its one of these
http://www.amazon.com/Zoo-Med-ReptiC...eating+element only in a 60w since my lamp is rated only for 75w max
"ReptiCare® Ceramic Heat Emitters are the perfect 24 hour heat source for all reptiles. These porcelain heating devices screw into a standard porcelain incandescent socket, giving off intense muscle-penetrating" infrared heat while emitting no light. The flat-faced design is more efficient and longer lasting than conical designs which build up excess heat internally ultimately carbonizing the element."