Flow indicator fittings include both simple visual indicators that show coolant flow or more complex flow sensors that translate flow data and send it to a controller or software. Visual flow indicator fittings are simple blocks of acrylic with standard G1/4 ports. Inside the acrylic block, an impeller rests loosely on a shaft of some kind. When coolant flows through the fitting the impeller is spun by the flow, giving an instant visual feedback on flow rates. Most flow sensors lack windows but are designed to connect to a controller of some kind that will display the flow rate data from the flow meter. Some visual flow indicators also have connectors for controller reading, providing both visual and electronic feedback. All three types are available from TITAN RIG in a range of colors and styles.