This 1 in calibrated flow measurement and balancing valve monitor system flow in low to medium flow rate HVAC unit, providing highly accurate flow measurement and adjustment. It consist of a brass and polyamide body with FNPT connection, integral patented technology that allow the reading and setting of flow rate without the need for instrumentation or tool. It is equipped with a GPM gauge to read flow and a hand wheel to set and lock the flow setting. Its ball valve construction allow full shut off capability and is ideal in hot/chilled water unit such as fan coil unit, water source heat pump, reheat coil, panel coil, small branch line, unit heater, unit ventilator, finned radiation and convector.