The 4 Jaw Grease Gun Coupler is designed for secure and leak-free grease application, ensuring efficient lubrication in high-pressure systems. The four hardened steel jaws provide a firm grip on standard grease fittings (zerk fittings), preventing grease leakage and reducing the risk of contamination. It is Universal fit, compatible with manual, pneumatic, and battery-powered grease guns. Made from high-quality steel for durable & corrosion-resistant to ensure longevity in harsh working conditions