Abstract: The subject of the invention is a valve for universal utilization and several purposes allowing by its formation the relatively high flow in the basic state and slightly open state of the valve even in case of small pressure differences in case of low pressure; furthermore the formation of the valve allows to ensure providing functions depending on the direction of flow that in given case can be regulated regarding back-pressure, partial back-pressure, pressure relief, partial relief limiting functions. The valve according to the invention is made in one piece from a soft, flexible material, and it has a full cross-sectional open basic part (2) at one end, and an intermediate part (3) of decreasing cross-section joining the said basic part (2), as well as a flattened part (4) joining the intermediate part (3) in the other end of the valve (1).