Series GX flow indicators have a single clear acrylic cylinder wall and are used to indicate flow or clarity of ultra-pure liquids such as demineralized water. They may also be used with corrosive chemicals that are compatible with acrylic. Plast-O-Matic flow and level indicators are designed to indicate the presence or clarity of liquid in a piping system or to indicate level in a tank. They offer a maximum viewing area with a full 360 degree visibility for dependable observation and inspection from a reasonable distance. With the exception of the Series GX flow indicator, which can only be used for liquids compatible with acrylic, all Plast-OMatic indicators utilize double-wall construction. O-ring seals are used on Series GX indicators allowing them to seal at extremely low pressures as well as high pressures. GX flow indicators are full ported, eliminating any possible flow resistance. Standard fasteners are stainless steel. The transparent outer cylinder wall is high impact strength acrylic. Optional fluttering streamers are corrosion resistant thermoplastic. Made of PVC.