TCP CFL Spring Lamp, 300W Equivalent, Cool White (4100K) MOGUL (E39) Base Spiral Light Bulb, 4200 Lumens Please note this CFL has a MOGUL base (larger than standard base - e39) Non Dimmable Lifetime: 9.1 years Uses 68 watts vs. 300 watt incandescent (with same light output) saving you $255 over life of the bulb Estimated Annual Energy Cost to Operate (based on 3 hrs/day): $8.00