Custom manufactured pneumatic selector (diverter) stack valves can handle multiple flows, in multiple directions, with multiple media. The valves can be manufactured to specification from a variety of materials such as aluminum, brass, and 316 stainless steel; with O-rings and sleeve materials to handle various media. Featuring virtually unlimited inputs and outputs, designs can range from 1 input to 9 outputs or vise-versa and include distinctive combinations of inputs and outputs. Designed to simplify piping arrangements and the potential for leakage by eliminating multiple valves, the valves are suitable for any mixing application. Stacking arrangements can range from 2 to 6 high and port sizes from 1/4″ to 3/4″..