3 way lamp socket has three lighting modes of low, medium and high, very practical (Please note that this feature is only available for dimmable bulbs). Product Features: Socket Type: Standard Medium E26/E27 Interior Only Interior Material: Phenolic, Knob Max Wattage: 250W Max Voltage: 250V On/Off Switch: Yes Circuit: 2 circuit 3- way Sequence: LO-MED-HI-OFF Bulb Type: Compatible with Incandescent, CFL or LED Package Included: 3 x Standard Medium E26/E27 Interior Can convert previous 1 way lamp to 3 way socket, just switch bulbs to 3 way after install