Each bulb has a standard E26 screw base.
. These bulbs are 250 watt each with a clear glass globe and finish. Included in this purchase are four double envelope T10 halogen bulb. Pack of 4Halogen Double Envelope T10 Medium Screw Base E26 Light Bulbs, 250 Watt, Clear, 4PK They are also available in a frosted finish.