... . >> Size : M20*140,M22*130 >> Material : Carbon steel >> Shape of head: Hexagon head >> Grade: 4.6,4.8,5.6,5.8,6 ... System and got the Production Permission License from the Ministry of Railways, P.R.China. 2.From 2006, we have ... certificates: 3. Product: Black( M20*140 ) & HDG( M22*130 ) square head screws 4. Factory view figures: PackagingFactory viewTesting equipmentsWorkshop Welcome your ...