https://www.superiorwasher.com/washers/8990/301-Stainless-Steel-Shims.html
This video describes shims, specifically those which are made from Grade 301 stainless steel – a material known for its strength and resistance against corrosion. 301 stainless steel shims offer a high level of toughness against breakage, compression or warping when used in various structural and architectural applications.
301 stainless steel shims are the preferred spacing solution in applications that often require creating clearances as well as incorporating and adjusting space between components.