Product Description The Yankee Hill Nelson (Nielsen-style) Booster Assembly is designed to replace the direct-thread adapter on YHM sound suppressors and other suppressors that use the common 1-3/8"-24 mounting thread. Built from durable 17-4 stainless steel with a matte black finish, this booster assembly is intended for use on handguns and barrels that require a Nielsen piston spring system to help ensure reliable cycling with a suppressor installed. Product Highlights Replaces a direct-thread adapter on suppressors that utilize the 1-3/8"-24 mount thread pitch Designed for handgun use where a Nielsen booster (piston spring system) is required Constructed from tough 17-4 stainless steel for long service life Matte black finish for a clean, low-glare appearance Note: piston is not included Specs Brand: Yankee Hill Manufacturer Part Number: 2055 UPC: 841812101215 Product Type: Nielsen/Nelson booster assembly (suppressor accessory) Mount Thread Pitch: 1-3/8"-24 Material: 17-4 Stainless Steel Finish/Color: Matte Black Country of Origin: USA Included: Booster assembly (piston not included) Disclaimer: We strive to provide accurate and up-to-date product descriptions, specifications, and images; however, errors or omissions may occasionally occur. We are not responsible for any inaccuracies or discrepancies in the content provided. If you notice anything incorrect or unclear, please contact us so we can correct it. When in doubt, we recommend verifying details directly with the products manufacturer.