J.W. Winco 6331-M12 DIN6331 Collar Nut, M12 x 1.75 mm, Steel: Amazon.com: Industrial & Scientific
DIN 6331 - Hexagon nuts with collar height 1.5 x D
100pcs) DIN 6331 M8 Hexagon Collar Nuts, Height 1,5 d A4 Stainless Steel, Ships Free in USA by Aspen Fasteners, ASSP633148: Amazon.com: Industrial & Scientific