A pump to produce or improve human penis erection includes a substantially tubular inner assembly having a rimmed annular edge suited to accommodate an erect human penis, a translating assembly sliding along the inner assembly having an end shaped like a dome with an opening or circular seat suited to accommodate a valve and a lid, a bellows having two annular edges suited to be connected and joined respectively with the rimmed annular edge of the inner assembly, where the valve has a first substantially disk-shaped part, the center of which has a second substantially linear part perpendicular to the disk-shaped part, and where the lid includes a circular element having an elongated hole or slot in a radial direction, through which the second linear part of the valve is housed and protrudes, as well as one or more additional through holes.
