Pressure

Old rusty pressure gauge screwed onto production barrel.

Camera Model: NIKON D3200
Aperture: 5.6
Focal Length: 55.0 mm (35 mm equivalent: 82.0 mm)
Exposure Time: 1/400
Lens: 18-55mm f/3.5-5.6

https://www.pond5.com/photo/116035716/pressure.html