These round, flat washers by Zenith are made from steel plate. Used under a nut to minimise surface or finish damage when tightening. They also spread load forces, preventing the nut from pulling into soft materials. Available in metric and imperial/BSW thread styles, as well as 4 finishes: Hot-Dipped Galvanised; Tech-Shield™ (for treated pine); Zinc-Plated; and Stainless Steel 304/316.
Contact your preferred store for product availability