The nipple is for all No. 11 percussion cap ignition systems with a ¼-28 thread. The nipple is machined from S7 impact resistant tool steel and hardened to Rc54-56 for maximum life. The nipple is designed with an optimized flame channel for reliable ignition and a concave face to redirect combustion gasses. We advise a drop of oil, or preferred, a quality lithium or molybdenum disulfide grease be used on the nipple threads before installation.