The LockNLube Grease Coupler doesn't pop off, doesn't leak, and easily releases with a thumb lever, even at extreme pressures. LockNLube has changed the way you connect to Zerk fittings with a patented sliding sleeve to lock the four hardened steel jaws onto the Zerk, creating a leak-free seal. No hands are needed to hold or align the coupler. You have both hands free to use your grease gun and know that grease is going in, not on, the machine. Stuck on couplers are a thing of the past. Just push down the thumb lever on your LockNLube Grease Coupler, and it comes right off, even on recessed fittings.