The LH0377 is an adapter for medium base sockets/lampholders. It allows a mogul base E39/E40 lamp to be used in a medium base E26 lampholder/socket. The LH0377 is not suited for HID lamps but can be used with incandescent, compact fluorescent or LED lamps in an HID socket. It has been referred to as a socket enlarger, lampholder reducer or socket converter. The LH0377 is rated at 660w and 250v.