Compatible Pitney Bowes DM300c / DM400c Ink Cartridge Red Royal Mail approved, compatible Pitney Bowes DM300c Red Ink Cartridge.100% guaranteed and supported by a 1 year warranty. The Pitney Bowes DM300c Ink Cartridge is guaranteed to work flawlessly with Pitney Bowes DM300c, DM400c 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.