U166 is a nickel plated brass bushing nut designed for Ø 12 mm (.472) threaded switches with 0.75 pitch thread, commonly used in series ID/S, IC-IH, IL, IM, IP, 660, 600H, 600N/H, 1000, 1200, 1500, 1600, 1700, 3600, and 4000. The nut features a nickel plated brass construction that provides corrosion resistance and durability for industrial and miniature switch applications. It is part of APEM's standard hardware lineup for panel switches and is supplied as standard hardware with compatible switch series. This component is essential for secure mounting and electrical connection of threaded bushings in control panel and industrial switch assemblies.