Hexagon 1/8" 1/4" 3/8" 1/2" 3/4" 1" BSP internal thread M10-/18 brass hexagon lock nut, with/without flange nickel plated
https://www.vogueparade.com/shopping/EN/200282142/1/1005002185808420/hexagon-18-14-38-12-34-1-bsp-internal-thread-m10-18-brass-hexagon-lock-nut-withwithout-flange-nickel-plated//