HILLMAN 880396 External Tooth Lock Washer, #4 ID, Steel, Zinc-Plated

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. The zinc finish provides rust resistance. Use with treated lumber in applications with like nuts and bolts of similar diameter.