"Bulb shape: ET-18. 20,000-hour average rated life. 250 watts. Brightness: 26,100 lumens. Bulb base: Mogul (E39). Size: 9-3/5""L x 2-1/4"" diameter. Lights exterior and large interior spaces efficiently at an economical price. NOTE: high-pressure sodium ballast (ANSI Code S50) required for operation. 6 bulbs per pack. For more on clean up...