... an electrical circuit. Used in various applications such as electric power,telecommunication, machinery, marine, textile, printing, miningindustrial equipment , and etc 3 ... .5mm 5.Other modles for reference:flush head,mashroom head,spring return,turn release,turn to stay up, ... dobble button,with ... ,self reset,convex,waterproof... ip66 waterproof pushbutton switch XB4-BP21,spring return