These 2-pin Philips lamps offer good color rendering and long life. They are suitable for use with preheat electromagnetic ballasts. * Rated Lamp Life: 10,000 hours * Base (5w, 7w): G23 * Base (13w): GX23 * Color Temperature: 2700 degrees Kelvin (except for the 13w 41K lamp, which is 4100 degrees Kelvin, and 13w 50K lamp, which is 5000 degrees Kelvin) * Color Rendering: 82 CRI * Light Output: 250 lumens (5w), 400 lumens (7w), 825 lumens (13w) * Length: 4.3" (5w), 5.3" (7w), 7" (13w) * Origin: Mexico