The YHM Nielsen Booster Assembly replaces the direct thread adapter on an AnechoX 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. Replaces your 1-3/8″-24 Adapter 17-4 Stainless Steel Matte Black Finish 1-3/8”-24 Mount Thread Pitch *DOES NOT INCLUDE PISTON* **NOT COMPATIBLE WITH SIDEWINDER PISTONS** Compatible Pistons: SilencerCo Rugged Dead Air Odessa