This Ushio 300 watt 115 volt BAH lamp has an E26 medium screw base. This bulb has a rated life of 20 hours and a luminous flux of 9,300LM. This A21 shaped bulb has an overall length of 4.93 inches and a 3200K color temperature.BaseE26 Medium ScrewBulb TypeIncandescent BulbsColor Temperature (K)3200KDiameter (in) 2.62Luminous Flux (LM)9300Maximum Overall Length (in) 4.93Rated Life (Hours)20ShapeA21Voltage (V)115VWattage (W)300W