JK Armament HUB Piston Mount .578x28 Black. The JK HUB Piston Mount installs in place of the JK 155 suppressors taper mount or other mount accessory threading directly into the base of the serialized suppressor tube with its HUB-standard 1-3/824 (1.37524) thread pitch. This also makes the JK HUB Piston Mount compatible with any other suppressor on the market with HUB threads and enough internal length to accommodate the booster housing (approx 1.8). Specifications for JK Armament HUB Piston Mount: Manufacturer: JK Armament Fabric/Material: Stainless Steel Aluminum Package Contents: JK Armament HUB Piston Mount JK Armament JK155HPM587X28BN: HUB Piston Mount .578x28 Black