The following statement has been released by Cheyenne regarding unofficial Hawk cartridges:
Fake cartridges leak, may be unsterile and grubbily packaged. Such cartridges are extremely dangerous, as they can spread contagious diseases! Also, due to the missing membrane they quickly destroy your machine. The Original Cheyenne cartridges completely seal the ink feed, so they do not leak through to your grip and machine. Your warranty will be void if your machine ever needs to be sent in for repair and its found that you have been using fake cartridges.
NB: This product comes with a 24 month warranty, which is valid direct with Cheyenne.