John Deere Hydraulic Coupler - TY2888 Coupling - COUPLER,SMALL DIAMETER HYDRAULIC. 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 extension, 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. This is a OEM John Deere part. Thanks for looking!