Zilla's energy saving Halogen Mini Dome Light is less than 5 inches in diameter. This tiny fixture accurately pinpoints heat and light into your terrarium, creating a small yet effective basking area for your pet. Mounts to your aquarium screen top with spring clips, keeping the fixture secure even when you access the interior of the tank. Place an energy efficient mini halogen bulb in the socket (sold separately) in white or blue for daytime viewing or red to watch your pet at night. Aluminum reflector dome keeps the light focused. 6 foot power cord.