The ESCO Pro Series 1.8 in. Mack King Pin Socket is designed to get the job done safer and easier while working on Mack trucks. Manufactured for use with 1/2 in. square drive ratchets and breakers bars. Designed to fit the slotted adjusting screw in tapered kingpins that are most commonly used on most Mack truck front axles (12,000 to 20,000 lbs.).