A keyless socket interior or keyless socket is not a typical lamp socket. It doesn't have a switch function so the circuit control needs to be performed by another mechanism. The keyless socket is the true "lamp holder" with no other purpose. Keyless sockets are ideal for pendant lamps (use a switch on the wall) or chandeliers (one switch controls all the lights) and some cluster lamps. 48204 - Leviton Brand Short Keyless Medium Base Socket Interior 40204G - Leviton Brand, Keyless Socket 40266 - Leviton Brand Keyless Plastic Medium Base Bakelite Socket The more complicated keyless socket is a 3-way socket. Designed for 3-way bulbs, the 3-way socket has the extra contact point on the base of the socket. 3-way bulbs have a low, medium, and high setting from having 2 sets of filaments. On-Off PushThru Socket Interior On/Off Turn Knob Socket Interior 3-Way Turn Knob Socket Interior 48220i - 3-Way Keyless Socket Interoir For the 3-way socket to work with the 3-way bulb, you will need a 3-way switch and wire it in the correct order. Our 40402 switches are 2 circuit and will work with a 3-way interior. 40402N - 3-Way 2 Circuit Nickel Rotary Switch Here is a wiring diagram to make it work: The switch has 4 positions and the socket has 3 screw terminals. As the diagram shows, the smooth lamp cord wire connects to the black wire of the switch. The ribbed lamp cord connects to the nickel screw terminal on the socket. The red wire is the first circuit to turn on so it connects to the brass plated screw terminal and the blue wire connects to the black screw terminal. In the 4th position of the switch, both red and blue wires are on the closed circuit and the 3-way bulb has both filaments lit.