SYLVANIA 40-Watt A15 -White- Ceiling Fan Bulbs - Intermdiate Base 2-Pack X22078 Vibration-resistant filaments will not fatigue easily from fan spinning or activity above Intermediate Size Bulb Base, These bulbs are Intermediate base, NOT Medium Base, and NOT chandelier base. Intermediate Size Bulb Base Operate In Horiztonal, Vertical, And Angeled Positions Approx. 1,000 Hours Total Life