Interstate Pneumatics CVH7048 - 1/4" NPT Pneumatic Air Flow Control Hand Lever Valve. Panel-mounting makes it convenient to install and apply. Hand Push / Pull Mechanical Valve. Mechanical valves are reversing valves controlled by external manual force. Normally used to control the output signal of pneumatic systems. Used for controlling pilots or diaphragms of larger valves or small cylinders or any pressure system that is alternatively pressurized and exhausted.