F(C)G-02/03 Series Pressure & Temperature Compensated Flow Control Valve, 10 to 1500 in³/min GPM Inlet Flow Range. Reverse Flow Check

You'll need either 5/16-18 x 2 Grade 8 socket head capscrews for the size -02 models or 3/8-16 x 3 Grade 8 socket head capscrews for the size -03 models. Eaton Vickers also sells bolt kits specifically for these valves, which might be easier than sourcing them separately.

With pressure and temperature compensation built in, the valve is meant to minimize flow variation when system pressure swings or the fluid warms up and cools down. You set flow with the dial, and it holds that setting more consistently across those changes than a non-compensated control.