High Quality Metal Internal Tooth Star Lock Washers Set Set Includes 8 Most Used Sizes: M3 M5 M6 M8 M10 Made of Metal Material, Very Good Corrosion Resistance, It Can Be Used in a Humid Environment. Package Quantity: 720-Piece, All of Washers Will Be Packed in A Sturdy Transparent Plastic Case, Can Be Use for A Storage Box A Lock washer exerts a spring force between the fasteners head and the substrate, which maintains the washer hard against the substrate and the bolt thread hard against the nut or substrate thread, creating more friction and resistance to rotation. Colour:As Shown Material:Metal Package Contents: 1 x 720PCS Internal Tooth Star Lock Washers Assortment Set(Spring pads:M3=50 pieces, =50 pieces, M5=50 pieces, M6=40 pieces, M8=30 pieces, M10=20 pieces, external teeth: M3=50 pieces, =50 pieces, M5=50 pieces Only, M6=40 pieces, M8=30 pieces, M10=20 pieces, internal teeth: M3=50 pieces, =50 pieces, M5=50 pieces, M6=40 pieces, M8=30 pieces, M10=20 pieces) Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.