This product is developed with reference of GB/T17880.2-1999 standard and the further improvement as per our customer’s actual requirements and our comprehensive market research; it is ribbed on both surfaces of round body and flange to grip better against rotation. It provides almost complete flat finish surface after riveting, however it is little bit inconvenient as the chamfer drilling is required. This product is commonly used in the mechanical parts where the high accuracy is required. This product is one of our flagship products and available from size of M4 to M12.