Halco Rapid Start linear fluorescent 40W T10 5000K (Designer Cool White), 88 CRI, 24000 hour lamp features the ability to operate on a magnetic or electronic ballast, replaces four standard T12 fluorescents with just two T10 Lamps. Trichromatic phosphors which improve visual performance and enhace color while providing high levels of illumination with outstanding color rendition and higher maintained light output over lamp life.