Features:

• 3-way funciton, turn-knob, phenolic socket
• Designed for 3-way bulbs
• Medium base (E26), sometimes referred to as standard or Edison base
• The bottom cap it tapped 1/8 IP, which measures 3/8" diameter
• The bottom cap also comes with a set screw for a more secure fit
• Rated 660 watts - 250 volts
• U.L. and CSA Listed

Turn-Knob 3-Way Phenolic Socket, Med. Base (E26), 1/8IP cap, no UNO threads, 250W- 250V, 3-piece set, with screw terminals.