McMaster 97135A250 High-Strength Steel Nylon-Insert Locknut, Pack of 10, Grade 8, Zinc Yellow-Chromate Plated, 1/2"-13 Thread

Versatile yet economical, these are the most commonly used locknuts. The nylon insert grips the screw to prevent loosening from moderate vibration without damaging threads. However, the insert may become brittle if exposed to high temperatures. These locknuts are reusable a handful of times, but the holding power decreases with each use.

High-Strength Steel — Rated Grade 8, Grade C, or Class 10, these locknuts are about 25% stronger than medium-strength steel nuts.

Zinc-Yellow-Chromate-Plated Steel — More durable finish than clear zinc plating, suitable for most wet and outdoor environments.