Full Vision Flow Sights are used in oil lines to allow visual observation of the flow and clarity of oil. The large size of the flow sight permits maximum visibility of the oil, even from a distance. They are often used at elevated heights to tell at a glance whether oil is circulating. The valves are tamperproof and dispense liquid at a specific flow rate.","Liquid flows downward through a nozzle in the sights. Each unit has a removable vent plug. The Pyrex (glass) sight chamber is normally vented when flow is discharged by gravity and closed when flow is discharged by low pressure. The unit withstands temperatures up to 225° F and a maximum pressure of 30 PSI. The body of the flow sight is aluminum alloy. Buna-N seals are used. The hex size is 1 ½ and the total height of the unit is 2.