Carlson Snap Caps allow for safe release of firing pin springs. A spring loaded striking area cushions and protects firing pins. An excellent tool for teaching and eliminating flinching. Two Snap Caps are included in each package. Prevents damage and prolongs main spring life, precision machined to true SAAMI specs, primer material is correct hardness to prevent striker/firing pin over-protrusion, and aluminum wont damage the chamber/extractor/ejector.