An irregularly shaped thread at the topof the nut grips the bolt for a stronger hold than nylon-insert locknuts. They thread on from the bottom of the nut, allowing more threads to engage the bolt before tightening for easier installation than center-lock distorted thread locknuts. The strength of the bolt should match the strength of the nut to prevent damaging threads. They're not reusable. Comparable in strength to Grade 8 bolts, they're about 25% stronger than medium-strength steel locknuts. The nuts have a 5/16-18 thread.
Black steel locknuts resist corrosion in wet environments.
