These 4-pin T6 circular lamps are used in TCP, Wilshire, and Huddardton Forge fixtures designed for use with a 40 or 58 watt 4 pin circular lamp. * Light Output (40w): 2,800 lumens * Light Output (58w): 3,700 lumens * Color Temperature: 2,850 degrees Kelvin * Color Rendering: 84 CRI * Minimum Start Temperature: -20 degrees Fahrenheit * Maximum Operating Temperature: 160 degrees * Fahrenheit Rated Lamp Life: 10,000 hours * Dimension (40w): 7.5" diameter, 0.75" thick * Dimension (58w): 9.0" diameter, 0.75" thick * Certifications: UL, CUL * Manufacturer Warranty: 1 Year * Origin: China