The 100w lamp is ideal to use at a distance of 18-24 inch from lamp to basking area for a basking temprature of 82-95°F. At the distance of 18-24 inch you will get a light spread diameter of 27.5-39 inch Ø. Infrared allows natural basking behaviour, as if the animal were in its own native enviroment. Infrared penetrates deep into the skin, activating many different chemical reactions and raising the core body temerature which aids optimal digestion.