COMPATIBLE PB RED INK CARTRIDGE: Use Save on Postage Ink for your compatible PB postage machine today! Our USPS certified red fluorescent 765-9 postage ink cartridge has DM 300c, 400c, 450c and 475c 765-9 compatibility. You can also buy our products assured knowing we offer full product protection and we will pay for machine damage parts & repair if any occurs.