There are a number of dealers, some of which are quite well-known, selling unauthorized Banshee Plate Carriers. Shellback Tactical owns the Banshee name and authentic Banshee Plate Carriers are only available through them or their authorized dealers.
If you purchase an unauthorized Banshee PC and happen to need warranty service, Shellback Tactical will not be able to help. This has become a large enough issue that they are working to add serialized labels and/or other authenticating marks.
The easiest way to ensure you have an authentic Banshee PC is to purchase directly from Shellback Tactical or one of their authorized dealers (see the most current list here). If the dealer you are shopping with is not on the list, it isn’t an authentic product. Shellback is updating the list weekly as new dealers come online. If you want to verify a dealer that you don’t see on the list just email firstname.lastname@example.org.