Keep your black powder rifle in peak condition with the Plunger Style FPJ Breech Plug from Knight Rifles. Designed to fit most Knight muzzle-loaders using our patented Full Plastic Jacket ignition system, this breech plug is compatible with the Wolverine 209, TK2000, American Knight, MK85, LK93, LK11, BK92, Bighorn, and Littlehorn series muzzleloaders. The breech plug plays a critical role in the performance of your muzzleloader, and Knight has built a reputation for innovation in the muzzleloading industry. Our redesigned breech plugs are specifically engineered to handle modern black powders, allowing you to shoot more and clean less. With Knight breech plugs, you can count on unmatched quality and reliability, ensuring your firearm performs at its best. Every breech plug is 100% American-made, reflecting our commitment to superior craftsmanship and durability. Fits all plunger guns including Bighorn, BK, LK, MK, USAK, Wolverine, Littlehorn, TK2000, T-bolt and HK, ensuring compatibility across a wide range of firearms If you have a .50 Cal, your breech plug diameter is 5/8-18 TPI, ensuring correct fitting for your firearm The full plastic jacket (FPJ) ignition system provides improved safety and reliability Hex head design, providing a more secure and reliable grip for fasteners