Reptile Basking Bulb Adapters; E27 standard thread to Halogen GU10, double pin, twist & lock, set of 2 These handy adapters will allow you to use the increasingly popular GU10 halogen basking bulbs with an E27 standard threaded socket. The GU10 Halogen Basking Bulbs are much more compact and dont require big dome style reflectors. This gives them much greater flexibility for planning your habitats basking areas. Their basking heat output is much more focused than traditional basking bulbs and their smaller size allow them to be used under the screen mesh common with many cages. This allows you to use lower wattage bulbs; better efficiency, economy and effectiveness!