Premium Material -- The flat head thumb screws are made of carbon steel with zinc plated. rust resistant. corrosion resistant and wear resistant. strong and durable. Product Size -- Specification: M5x12mm (thread length); Head Diameter: 16mm/0.63"; Height: 22mm/0.86". Note: Please check the size before purchase. Easy to Use -- The knurled head design provides best gripping. easy to tighten and loosen the screws without any tools. A best choice for fastener. the surface is well-made. smoothly without burr. Widely Application -- The m4 knurled knobs widely applied in machinery equipment. communication equipment. electronic equipment. automotive industry. building and bridges. instruments. lighting product and so on. Satisfactory After-Sales Service -- Uenhoy is devoted to providing high quality service. Please feel free to contact us if the item has any quality problem. Your satisfaction is our biggest power.