I got this on a wet-brained evening wanting it to be a Smith Vortex 5.56. I blame it on the guys photo. Any how it is as new never fired SKU: HKNA4PRONG28 includes the rubber seal. This can be used on 9mm AR...or any 9mm pistol w/1/2x28 pitch. I would love to trade for a used 5.56 Vortex hider or $45.00 Shipped USPS MO. FTF available Molalla/WoodBurn/OC upon request. Thanks for the help. I DON'T HAVE A USE/PROJECT FOR THIS SO....MAKE AN OFFER...IF SOMEONE ELSE COULD PUT IT TO USE, I'D BE SMILES