The LockNLube Grease Coupler's 1/8" NPT threads are compatible with any grease gun; pneumatic, manual, or battery-operated. It is rated to pressures of 10,000 psi, does not leak, and will not pop off under pressure, says the company. After greasing, press the thumb lever to release the coupler from the Zerk fitting. The 5/8" OD is only 1mm larger in diameter than a standard coupler. Users can grease without the mess or concern associated with leaking grease, releasing under pressure, or fighting to break free from stubborn fittings.