This product is developed with reference of GB/T17880.4-1999 standard with some variation on the size of the product 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 rotaion. The test resuIts confirm the torque of the product has largely exceeded the requirement in above Standard. It provides almost complete flat finished surface after riveting because of its small and thin head. This product has become one of our flagship products with size from M4 to M12 and from 6# to 1/2UNC as per American standard and 5/32 of British Standard.