RT 90A CE390A Modified MICR Toner Cartridge for Check Printing on LaserJet Enterprise 600, M601, M602, M603, M4555 series printers Lifetime Warranty. We always honor our warranty, even if the Amazon return window has closed. Contact us directly with any questions or issues. Modified MICR Cartridge with RT magnetic toner for check printing OEM #: CE390A / 90A | Yield: 10k pages at 5% coverage; prints 30k checks @ 3 per page For use in HP LaserJet Enterprise Printers: 600, M601, M601n, M601dn, M602, M602n, M602dn, M602x, M603, M603n, M603dn, M603xh, M4555f, M4555h, M4555fskm MFP RT is the manufacturer of this MICR toner cartridge. The listing of any RT product is not intended to imply any endorsement or direct affiliation with the OEM trademark owner.