The Rugged 3 Lug Adapter features their patented Go/No Go Gauge. The No Go/Go Gauge provides confirmation that your suppressor is properly attached, for a surprise free shooting experience. The 3 Lug Adapter is compatible and used in conjunction with the Rugged 3 Lug Mount as well as any H&K patterned 3-lug mount. *Rugged recommends using Red Loctite and 20-25 ft-lbs to torque the 3 Lug Adapters onto your barrel.