Pitney Bowes 797 Blue Compatible Postal Ink Cartridge for DM50, DM55, K700, K780002, K721 100% Guarantee or your money back - Ships within 24 hours or next business day Works with Pitney Bowes DM50, Pitney Bowes DM55, Pitney Bowes K780002, Pitney Bowes 721 Approx. 800 impressions