CISinks Refillable Ink Cartridge Set for HP 934 935 Officejet Pro 6230 6830 6835 Officejet 6812 6815 6820 (HP934 / HP935) Save Money over OEM inks Easy to install, Instructions included Printer modifications may be required Compatible With: HP Officejet Pro 6230 6830 6835 Officejet 6812 6815 6820 The systems/cartridges will leak once the pedestals are removed. This is not a flaw with the system but it is due to the sponge that is built into the cartridge. Make sure to set up a work area and use gloves.