SCHOTTEL OEM hexagon socket head screw plug. Closes a threaded port on the propulsion housing — typically an oil drain, oil fill, level inspection or magnetic-plug port. Replaced together with its sealing washer (USIT-Ring) at every oil service. Note: this part number identifies the SCHOTTEL part family. The exact dimensional or material specification on the as-supplied part may require confirmation against the vessel serial number and equipment data plate — confirm with the vessel's SCHOTTEL service file before final order.