1. 3SU1900-0AC81-0AA0 is an Emergency Stop Push Button for Siemens controls.
2. This part is designed for use in machine control systems to stop a machine or process quickly and reliably.
3. It comes with a red mushroom-shaped head, visible from all sides when activated, which can be pressed from either side. It also has an emergency stop cable with an integrated emergency stop switch and can be used with various other emergency stop switches.