https://www.fastenerdata.co.uk/fasteners/washers/flat/hard-hardened-flat-washers.html
Fastenerdata - Hardened Washer - Fastener Specifications
Hardened Washer in metric and in Inch for USA and UK markets. Hardened Flat washers are used under bolt heads or nuts to increase the bearing area and to offer...
hardened washerfastenerdataspecifications