Hillman 5/16 in. Stainless Steel External Tooth Lock Washer (50-Pack)

Designed with sharp teeth as a great locking mechanism, tooth lock washers create a ratchet action by biting into the material and surfaces they contact. Ideal for situations where potential loosening from corrosion or vibration is a concern, tooth lock washers are used to prevent nuts and bolts from coming loose. These fasteners contain teeth around the outer diameter that help bite into the joint material, thus providing a locking feature when tightened beneath a nut. Use with treated lumber in applications with like nuts and bolts of similar diameter.