Continuing in our tradition of bringing innovation to the muzzleloading industry, we redesigned our breech plugs to better accommodate todays modern black powders. The fixed vent breech plug provides 40% longer life and drastically less blowback. Now you can shoot more and clean less! Vent liner is fixed and non-removable. Fits: W209, TK2000, USAK, MK, LK, BK, BH, and LH Uses Full Plastic Jacket Hex Head