This product includes: 4-Pack Black 521H 52D1H00 Lexmark MS811dn compatible toner cartridge Compatible Printers: Lexmark 521H MS810de, MS810dn, MS810dtn, MS810n, MS811n, MS811dn, MS812dn, MS812dtn, MS812de, MS811dtn Print the same number of pages as the original Lexmark 521H Black Page Yield*: 25,000 Average cartridge Page Yield* in accordance with ISO-19752. *at 5% coverage (ISO/IEC standard) 521h toner is the high yield version of Lexmark 52D1000 with 6,000 Page Yield*. *at 5% coverage (ISO/IEC standard) Please contact us first with any product issues. We want all of our customers to be happy because happiness matters.