4-jaw hydraulic coupler for use with hand operated grease guns. This coupler features a small outside diameter to permit easy contact with recessed fittings. It fits hand operated grease guns using a 1/8″ NPT male extention, to its 1/8″ NPT female port. The body section has a knurled pattern tightening into place for use. The maximum working pressure is 6,000 PSI, and a burst pressure rating of 10,000 PSI.