This is an authentic manufacturer-sourced replacement seal which is specially designed for use with Senco staplers and pinners. It is utilized to provide an air-tight seal for the valve, over time it may begin to shrink, become brittle and crack eventually requiring replacement to maintain peak performance. Please note this high-quality rubber seal is sold individually. For Use With: Jet L (LG45-3/4) Stapler L (LN3045-1) Stapler L (LN4450-1) Stapler L (LG4450-1) Stapler L (LN2532-3/4) Stapler LS1 18 Ga. Headless Pinner