PETOL HAMMERTIGHT Wrench Retainers are safe and easy-to-use tools designed to hold a striking wrench (also called a slugging or hammer wrench) on a nut for a safer, hands free, one man operation. The HAMMERTIGHT tool easily threads onto the stud. A spring loaded plate enables the wrench to be repositioned on the nut without removing the retainer. Specifications: Fits Stud Size: 39mm – 4.0 Nut Size: 60mm Overall Length: 2-7/8" Weight: 1-5/8 lbs. How it works: Place wrench on nut and thread retainer onto stud. Lift up on wrench to compress spring loaded retaining plate. Reposition wrench on nut and release spring loaded plate and continue.