Stainless steel deck filler. The unit is designed to accept suction hoses of sanitation waste treatment areas. Hose connection: 38 mm, outer diameter: 76 mm.
Good workmanship, nice design. Key to unscrew the lock included. Closure is secured with a small chain on the inside of the suction nozzle, which makes little sense, since the disposal hose is also screwed on. The superfluous chain can simply be unscrewed.