By using the finest blend of premium trichromatic rare earth phosphors these lamps provide 50% more lumens than their nearest competitor. The exclusive built-in cathode guard extends the lamp's useful life while preventing unsightly "lamp end darkening". TCLP compliant as a low mercury lamp. Combine all these features with high quality full spectrum 'Daylight" 5000 K, 88 CRI & pricing for a "Best Buy".