Fluker's incandescent daylight bulb provide the radiant heat (infrared light) that reptiles need. Reptiles are exothermic and depend on their environmental temperature to regulate their core body temperature. If a reptile is not provided an appropriate environmental temperature range (ETR), it may be predisposed to chronic infections. Because ETR's vary from species to species, ask your pet professional for guidance in determining the appropriate ETR for your pet. Available in 150-watt bulb and blue color.