Enjoy accurate, consistent color and the best performance your HP printer has to offer with HP 645A LaserJet Toner Cartridges-the all-in-one design that makes high-quality color printing easy, reliable, and cost-effective. Chemically-grown toner formulas in HP toner cartridges are designed together with the printer. The uniform size and spherical shape of HP toner particles ensure a broad range of colors and precise control and placement for accurate color and precise image reproduction.