The Exo Terra Glow Light gives you the versatility of placing heat and/or light sources on your terrarium where needed. The device is sturdily constructed, with a metal reflector, heat resistant ceramic socket, and a spring-loaded swivel clamp. It can be easily turned off and on by the switch, mounted on the extra long power cord. The inside of the reflector is coated with a highly reflective luminous coating that continues to glow long after the lamp is turned off. This allows diurnal reptiles and amphibians to retreat in their night burrow or hiding without stress. A moon-like glow enables nocturnal reptiles and amphibians to see properly without disturbing their night cycle. It is also ideal to monitor your animals during night time, without switching on the lights which can cause stress and disorientation. This multi-purpose fixture fits a variety of screw-based bulbs including the Exo Terra Daytime Heat Lamp, Intense Basking Spot, Daylight Basking Spot, Halogen Basking Spot, Repti Glo Compact 2.0, 5.0 & 10.0, Infrared Basking Spot etc. The coating reflects the otherwise wasted light rays and stores the light energy during daytime and slowly releases it at night, which makes this fixture more energy efficient than conventional fixtures. This means there is no need to add an additional night bulb, unless used as a heating source. One or more Exo Terra Glow Lights can be mounted on the rim of the terrarium or aquarium and directed to the basking area with the spring-loaded swivel clamp or it can be put on top of a metal screen cover in any desired location. The Exo Terra Glow Lights are available in 3 sizes. - PT2052 - Exo Terra Glow Light & Reflector Small 14cm / 5.5"- PT2054 - Exo Terra Glow Light & Reflector Medium 21cm / 8.5"- PT2056 - Exo Terra Glow Light & Reflector Large 25cm / 10" Please Note: The Exo Terra Glow Light models are NOT to be used with the Exo Terra Terrariums, use the Exo Terra Light Dome instead in conjunction with the Exo Terra Light Bracket.