KQ2 one-touch, metric and inch size fittings are available in a wide variety of sizes, body styles and thread types. The specially designed packing provides positive sealing under pressure without the reduced flow common with compression fittings. The KQ2 release collar releases both the chuck and collet to provide a low disconnection force for easy removal of the tubing. KQ2 fittings are

KQ2 one-touch, metric and inch size fittings are available in a wide variety of sizes, body styles and thread types. The specially designed packing provides positive sealing under pressure without the reduced flow common with compression fittings. The KQ2 release collar releases both the chuck and collet to provide a low disconnection force for easy removal of the tubing. KQ2 fittings are

CONTROL UNIT WITH MANIFOLD VALVE, 4/5 PORT SOLENOID VALVE, J55, 1.1 lb

Consider a VFS4600 series 3-position perfect type valve.
For the VFS4300 series 3-position closed center valve with a metal seal, some air leakage is unavoidable even in the neutral position and even if there is no air leaking from the cylinder or joint.
Further details can be found here