Specification: Maximum Overal Length of 18 Inches, 15 Watts, 4000K Cool White 800 Lumens, Diameter 1.5 Inches(it is not 1 inches), G13 ( Medium Bi-Pin Base) Average Lifetime: 9000 hours, The defective ballast inside your fixture will cause the bulb do not work, please check the fixture ballast before purchasing Packing: 21532, F15T12/DCW/RP and F15T12CW 15W cool white fluorescent light bulb Widely use: Ideal solution for commercial,industrial applications After-sales service: Please contact our 24/7 customer support T12 15 Watt Fluorescent Bulb, 18 Inches F15T12/CW Straight Tube, Medium Bi-Pin Base, Cool White 4000K 800 Lumens 2 Count