Heavy-duty 4-jaw hydraulic coupler is excellent for heavy-duty greasing applications. This coupler features a ball check to prevent leakage and loss of pressure. It fits standard grease guns using a 1/8 inch NPT male extention. The coupler is 2 1/8 inch long, with 1/8 inch NPT female port and a hex section in the body for tightening with a wrench. The maximum working pressure is 8,000 PSI and a burst pressure rating of 24,000 PSI.