as bearing surfaces for the fingers of the user in its upper portion the cylindrical part 111 comprises a transverse wall whose central zone is cut out and is surrounded by an annular flange 131 the second valve 113 of the dispensing head is positioned in the zone delimited by the flange 131 and is applied against the flange 131 by the annular washer 117 arranged at one of the ends of a cylindrical skirt 119 the relative centering of the valve 113 and the skirt 119 is ensured by a circular rib 127 provided on the washer 117 which cooperates with a groove 126 arranged on one of the parts of the valve 113 a helical spring 120 bears on the end bead of the cylindrical wall 122 and the bead cooperates with a complementary bead of the cylindrical part 111 for limiting the travel of the push button in the direction of the action exerted by the spring 120 the spring 120 is disposed in the annular space between the cylindrical part 111 and the skirt 119 and it bears on one side against washer 117 and on the other side against the end bead of the cylindrical wall 122 thus the spring 120 maintains the valve 113 in bearing contact against the flange 131 the valve 113 consists of two caps 114 and 115 nested one in the other the lower cap 114 being made of a relatively rigid plastic material and the cap 115 being made of a flexible plastic material the cap 114 comprises a first flange 125 provided on its side nearer the.