(37a MICR) HP LaserJet Enterprise flow MFP M631h, M632z, M633z and Enterprise M607, M608, M609, M631, M632, M633 series laser printers - Black MICR toner Cartridge for printing checks (approx. 11,000 page yield) (MICR version of HP #CF237A). The patented security agent forces a bright red stain to permeate through the document if chemical alteration is attempted.

(37x MICR) HP LaserJet Enterprise flow MFP M631h, M632z, M633z and Enterprise M608, M609, M631, M632, M633 series laser printers - High Yield Black MICR toner Cartridge for printing checks (approx. 25,000 page yield) (does not work in M607 model). The patented security agent forces a bright red stain to permeate through the document if chemical alteration is attempted.