Professional Rivet factory since 1988. stainless steel monobolttype: cup head , countersunk headmaterial: stainless steel/stainless steelsize:cup head: 4.8*10, 4.8*14, 6.4x14, 6.4*20mmcountersunk head: 4.8*12, 4.8*16, 6.4*16, 6.4*22mmsurface: polish, Cr3+ zinc