Sight Flow Indicator Factory: Dual Glass Window Type, High Pressure, 6 Inch, DN150, Class 300 LB, PN50, RF Flange Ends. Browse our range of sight flow indicators with dual glass window type, designed for high-pressure applications. Available in a 6-inch size (DN150), these indicators are rated for Class 300 LB and PN50 pressure ratings. The indicators feature RF flange ends for easy installation. Shop now for reliable and efficient sight flow indicators for your industrial needs.