An excellent light source for digital, video...even daylight-color film. While other fluorescent lamps have a Color Rendering Index of only between 60 to 80 (100 CRI is perfect), ColorMaster spiral fluorescent lamps are rated at 93 CRI for vivid and natural color rendering, without the washed-out and poor color reproduction of other bulbs. With a life of 10,000 hours, 5500° daylight color temperature and low heat, a ColorMaster lamp is an excellent light source for many studio applications. Fits fixtures that accept household-threaded incandescent bulbs. 540234 uses 30 watts of power, but has the brightness of 120 watt incandescent lamps. Measures 2-3/4" diameter by 6-1/4" long. 540256 uses 50 watts of power, but has the brightness of 200 watt incandescent lamps. Measures 3" diameter by 8-1/2" long.