M2B Process Sealed Miniature Pushbuttons NKK Switches M2B Process Sealed Miniature Pushbuttons feature a snap-acting contact mechanism that gives short travel, sensitive actuation, light touch, smooth feel, audible feedback, and a longer electrical life. The single unit construction of the bushing housing and O-ring surrounding the actuator gives protection from cleaning fluids or other liquids. The NKK Switches M2B Series Process Sealed Miniature Pushbuttons have upper and lower housings that are ultrasonic welded to seal out contaminants and allows automated soldering and cleaning.