... spring steel ,stainless steel,carbon steel,etc Surface: Zinc plated or Black Size: M6-M100(1/4-4inch) Features: 1.Flat washer and Spring ... , 9021),BA,NFE,JIS,and according to customers' requirements.3.MaterialCarbon steel,45#,65Mn,stainless steel,brass4.FinishPlain;black; zinc ... quality control from producing to delivery. Stainless steel/galvanized steel spring washer and flat washer,tapper washer