material:carbon steel,middle carbon steel 45#50#,stainless steel ss304,316 size:M2-M80 surface treatment:Z.P/H.D.G/black/plain DIN125 falt washer material:carbon steel,middle carbon steel 45#50#,stainless steel ss304,316size:M2-M80surface treatment:Z.P/H.D.G/black/plain