[SIZE]: Width Measured From Flat to Flat 13mm / 0.51"; Height 8mm / 0.31". [MATERIAL]: Made of carbon steel, surface is Zinc-plated for good rust resistance. [FEATURE]: With a nylon insert, these lock nuts greatly reduce loosening under vibrations and torque. [ADVANTAGE]:Our hex lock nuts are strong and durable to use. Surface galvanizing has a corrosion-resistant effect. [APPLICATION]: Can be widely used in automobile, construction machinery, shipbuilding and etc. Quantity: 50 pieces Note: It does not include other things, the color is based on the first picture, and the other pictures only show the effect Due to the differences between different monitors, the picture may not reflect the actual color of the item. Due to manual measurement. Please allow deviation. Thanks!