I bought compatible cartridges for my HP Officejet Pro printer at a very good price. delivery was excellent and the advice form Cartridge Shop was thorough. The cartridges should work with my printer, if not, the money-back guarantee would come into operation. I received the cartridges and inserted them in the almost new printer, but unfortunately they would not work due to HP security. I talked to Cartrdige Company, they guided me through several trials to get them working, but failed. Subsequently I was given full credit for the purchase as promised. I have used this Copany many times and trust them implicitly.