Porcelain ceiling lampholders - keyless feature high strength insulator porcelain. Mounts on 4 in. (101.6mm) outlet boxes with breakout for 3.25 in. (82.55mm) box mounting. Pull chain socket interiors are removable. Pull chain devices include ball chain, 3 ft (0.91m) of cord, connector and end bell. Top wire versions have terminal screws backed out - ready for wiring - without removing the interior. Sockets available in two piece version to permit interior replacement, dust ring protects against plaster and dirt. Shade grooves provided on two piece version.