Air-Tech's red visual regulating valves give you instant feedback of air flow to each outlet, and its easy-dial controls allow precise changes to air output. Air-Tech also offers other well-designed features, like: a flip-top cover to keep valves clean; an extra input/output for an additional pump or valve; non-corrosive all-plastic construction; and an adjustable hanger which fits any tank. Its top-of-tank location also naturally eliminates back-siphon.