The LH0421 Leviton 30 is an E26/E27 medium base porcelain two piece lamp holder (socket) with a center hole for a power cord. This lampholder (socket) is two-piece porcelain and keyless socket that comes with two 8-32 x 1/2 inch long mounting screws The LH0421 Leviton 30 measures 1.75 x 1.75 x 2.31 inches.