The Big Gator Tools Original G. Coupler Long Series is a grease coupler tool designed to allow users to be handsfree while greasing. This patented, lock-on mechanism helps prevent mess and wasted grease. The coupler has a spring-loaded activation trigger. The lock-on mechanism has four hardened spring steel jaws that grasp onto the Zerk. A high pressure seal helps reduce leakage. This coupler is designed to work with all grease gun types, the company says.