... for use with banjo bolts and rings .Washer Type: Copper washer,aluminium washer,O-ring,Twin rings,heat shield Twinrings were developed ... for use with banjo bolts and rings.2.Materials: Copper, Aluminium, AIMg3, AIMgSi1, Steel, Armco, Spring Steel (Ck67,Ck75, 51CrV4, etc ... to order according to the request of anyone too flat copper washer,aluminium washer