ISINK34 or 4135554T Compatible Replacement Cartridge for Neopost IS330, IS350, IS420, IS440, IS460, IS480 Mailing Machines. Compatible postage ink cartridge compares to ISINK34 and IMINK34. For use in IS330, IS350, IS420, IS440, IS460, IS480, IS490 Postage Meters Fluorescent Red ink meets all USPS regulations Great product at fantastic savings!