1Place of origin:Shenzhen Guangdong China(mainland) 2Material:brass 3Size:M1.0-M8 knurled brass inserts 1Place of origin:Shenzhen Guangdong China(mainland)2Material:brass3Size:M1.0-M8 4Type: zig-zag , twill , Blind hole , checkered ,etc5Certificate:ISO 9001 2008 ,RHOS6Sample is welcome ,we also receive OEM knurled brass inserts