1.Thin type knurled thumb nuts. This is a carbon steel knurled nut. 2.The circular nut with knurled is easy to assemble and disassemble.3.Made of good quality carbon steel material, zinc plated finish, corrosion-resistant. Specification:Material: Carbon SteelFinish: Blue Zinc PlatedThread Size: M3 x 0.5mmOutter Diameter: 11mm / 0.43"Height: 3mm / 0.12"Package Content: 10 x Knurled Nuts