M3 M4 M5 M6 M8 M10 M12 M14 M16 M18 M20 M24 304 Stainless Steel External/Internal Toothed Serrated Lock Washer
https://www.vogueparade.com/shopping/EN/42/1/1005003636180035/m3-m4-m5-m6-m8-m10-m12-m14-m16-m18-m20-m24-304-stainless-steel-externalinternal-toothed-serrated-lock-washer//