Ensure the optimal performance and longevity of your JP Silent captured spring or Variable Mass Operating system (VMOS) bolt carrier with our comprehensive O-ring replacement kit. Designed to seamlessly replace any worn, deformed or lost O-rings, this kit is essential for maintaining the integrity and functionality of your firearm's operating system. Regular inspection and timely replacement of O-rings are crucial, especially when signs of fraying or cracking appear. This is particularly important for 9mm carbines, where O-ring wear may become evident after approximately 5,000 rounds. Our kit not only includes high-quality replacement O-rings but also provides a spacer shim and snap rings to ensure precise fitment. Additionally, a replacement retaining screw is included to secure all components effectively. With this all-inclusive kit, you can confidently maintain your firearm's performance, ensuring smooth operation and reliability. Whether you're a professional shooter or an enthusiast, this O-ring replacement kit is a must-have for your maintenance toolkit.The package contains replacement O-rings, a spacer shim and snap rings for the JPSCS to ensure proper fitment, as well as a replacement retaining screw