These nuts are 5/8" hex and 1-11/16" long and are designed to be used with our main cap stud kits for small and big-block Chevrolet engines. They offer an alternative method for attaching a windage tray. When used to attach an oil pump with our oil pump stud they provide an easy method for bolting a support strap to the oil pump pickup. B&B Windage Tray Stand Nuts are made from 4130 chrome-moly steel and feature 3/8-24 threads for secure mounting of the windage tray.