The CTA Mack Truck King Pin Socket, No. 5044, is designed to fit the slotted adjusting screw on tapered kingpins found on most Mack front axles (12,000 lbs, 16,000 lbs, 18,000 lbs, and 20,000 lbs). The cross design of kingpin caps is designed to reduce the camming or walking action caused by other methods. Use with a 1/2" square drive ratchet or breaker bar to safely remove the pin.