Page Yield*: (6,000 pages) compatible with Lexmark 521 Laser (Black) (per cartridge) *at 5% coverage (ISO/IEC standard) Package Contents: 4 x 521 Black compatible toner cartridges Standard Yield 52D1000 Compatible with: MS810de, MS810dn, MS810dtn, MS810n, MS811dn, MS811dtn, MS811n, MS812de, MS812dn, and MS812dtn Product name: LD Products 521, 52D1000 Compatible Toner Cartridge replacement for Lexmark 521, 52D1000 Toner cartridges for Lexmark 52152D1000 Professional compatible replacements manufactured by LD Products. Lexmark is a registered trademark of Lexmark and is not affiliated with and does not endorse LD Products