120pcs m4 m5 m6 m8 m10 zinc inside and outside teeth screw insert hex nuts assortment kit

made of material, high strength, durable in use. groove spacing neat and consistent, rotary smooth fastening. both inside and outside have teeth lines, and can be embedded in the plastic, aluminum alloy cast iron, copper and other soft materials. come with a transparent storage case for quick access and protection. widely used in automobile industry, rail car industry, shipbuilding industry, household appliances, construction machinery, business machines, electronic products, engineering plastics, adva.......syi