Lampholders mount on 4" (101.6mm) outlet boxes with breakout for 3.25" (82.5mm) box mounting. Leads are 6" (152.4mm) 221ºF (105ºC) insulated stranded #16, stripped 0.75" (19.0mm). Pull chain devices include ball chain, 3' (0.9m) of cord, connector and end bell. Top wire versions have terminal screws backed out ready for wiring without removing interior. Porcelain models made with high-strength insulator porcelain; pull chain versions feature removable interiors.