Sight glasses can be mounted in different places in a loading/unloading system to allow for visual flow control through a transparent glass fitted in a coupling. The sight glasses are made of aluminium or brass. Available sizes: 2″, 3″ and 4″ with a number of connection options: male thread, female thread, flange, CAMLOCK. The sight glasses are widely used in fuel, petrochemical and chemical loading/unloading applications.