The U840 is a miniature momentary pushbutton switch cap component from APEM's 9000 series product line. It is designed to fit with a 6.35 DIA-40UNS (1/4-40UNS) threaded mounting and is compatible with the U480 standard cap base. The cap is available in multiple color options including blue, black, green, grey, yellow, red, white, and orange, allowing for customizable visual identification in control panel applications. This component is chrome plated and ordered separately from the base switch assembly. The U840 cap is commonly used in industrial control systems, machinery interfaces, and operator panels where color-coded pushbutton identification is required.