internal tooth washer Materials:400 series stainless steel Size:For No.4-No.12,1/4"-1/2" bolt Washer style:internal tooth Features:AISI B18.21.1 SUS410 internal tooth washer StandardDIN137, DIN 6797. DIN6798, ANSI B 18.21.1 Material C1010-C1022, 65Mn, stainless steel A2, A4 grade, or other alloy steel as per your need. Surface Finish plain, zinc plated of various colour, hot dip galvanized, ...