Product DescriptionThe JP Silent Captured Spring System is manufactured exclusively for Maxim Defense Industries to work with the Maxim Defense CQB Stock System. Built for 9mm AR-platform configurations and made with tungsten and stainless steel components, this captured spring system helps streamline cycling by integrating the spring and guide rod assembly. It requires an open channel in your bolt carrier group assembly for the guide rod to pass during fire.Product Highlights JP Silent Captured Spring System made exclusively for use with the Maxim Defense CQB Stock System 9mm weight configuration designed for AR 9mm platform builds Tungsten and stainless steel construction for durability and proper mass Captured spring/guide rod design helps reduce traditional buffer spring noise and vibration Requires an open-channel bolt carrier group to allow guide rod travel during firingSpecs Brand: Maxim Manufacturer Part Number: MXM47572 UPC: 680017475727 Platform: AR-platform / AR9 Caliber/Type: 9mm weight Silent Captured Spring system Material: Tungsten / Stainless Steel Compatibility: Maxim Defense CQB Stock System Installation Note: Requires an open channel in the bolt carrier group for the guide rod to pass during fireDisclaimer: 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.