The YHM Nielsen Booster Assembly replaces the direct thread adapter on a YHM Sound suppressor or any other suppressor on the market which utilizes the 1-3/8"-24 thread. They are designed to be used on handguns and barrels which require a Nielsen Booster. Compatible Pistons: Silencerco Rugged Deadair Odessa Features: Replaces your 1-3/8"-24 Adapter 17-4 Stainless Steel Black Oxide 1-3/8"-24 Mount Thread Pitch *DOES NOT INCLUDE PISTON* **NOT COMPATABLE WITH SIDEWINDER PISTONS**