Hard steel washers Size:For No.4-No.12 screw,1/4"-1/2" Certification: ISO9001, ISO14001 Advantage:senior workers of 15 year Features: Hard steel washers 50% savings 1.StandardDIN137, DIN 6797. DIN6798, ANSI B 18.21.1,GBT9074 2.Material C1010-C1022, 65Mn, stainless steel A2, A4 grade, or other alloy steel as per your need. 3.Surface Finish plain, zinc plated of various colour, hot dip galvanized, ...