303 Stainless Steel Gasketed Window Sights allow visual observation of liquid levels and their condition. Stainless steel is resistant to corrosion, rust, and staining.  It maintains its appearance over long periods and minimizes unwanted bonding between parts.  These window sights may be mounted into any corresponding pipe thread. They can be used to display fluid motion or mechanical movements, as well as to view and perform tests in a safe enclosure. Specific uses include fluid sighting on hydraulic tanks, pressure vessels, reservoirs, packaged power equipment, hydraulic lines and dipping. Their use can be applied to any application where oil or fluid inspection is essential.