Dia:4.2-4.8-5.5 Length:13-63mm Material:carbon/stainless steel Finish:zinc/yellow zinc/blue zinc/phosphated Length:13-200 Standard:G/A/I/D/J Packing:negotiable Advantage: high quality with professional technology and resonable price They have wonderfull corossion resistance. stainless steel screw, self drilling screw #3-5pnt can drill 4.4-16m/m steel sheet They have wonderfull corossion resistant.