These fittings are suitable for the dead space-free shut-off and dosing of problematic media. While the diaphragm valves can only be used for liquids, pinch valves can be used with almost all media and substances (even abrasive, fibrous, corrosive, powder, etc.). Here the medium is guided through a hose shaped diaphragm which can be pressurised with compressed air from outside, and is pressed together from the outside pressure. Even granulate, dusts, gravel, cement and sand can be dosed easily and without clogging.