Compatible Pitney Bowes DM50 Ink Cartridge Red Royal Mail approved, compatible Pitney Bowes DM50 Red Ink Cartridge.100% guaranteed and supported by a 1 year warranty. The Pitney Bowes DM50 Ink Cartridge is guaranteed to work flawlessly with Pitney Bowes DM55i, K700 franking machines. Why pay more than double for your Ink Cartridges from Pitney Bowes when you can buy a guaranteed product, supplied at a fraction of the cost.