Spiral thread: The thread has a tightening effect, the surface is smooth and flat, there is no residual burr, it is not slippery in use, and there is no phenomenon of missing teeth. Standard external hexagon: The external hexagon is clear and tidy, and the specifications are all standard. There is no offset in the center of the head. Head Type: Hex Material: Stainless Steel Measurement: Metric Type: Serrated Flange Quantity: 20 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!