ZB4BG4 is a 45-millimeter target-type emergency stop push button from Schneider Electric, part of its Zelio range of industrial control and automation products. It has a light green unit with a yellow push button. The faceplate is marked with a red octagonal emergency stop symbol, and it is rated up to 600V AC. It is a four-pole device with 2 N/O contacts and 2 N/C contacts, and uses an IP66-rated polyamide housing for protection.