from returning into the first conduit 2 as the air in the first chamber 6 is compressed the pressure in the first chamber 6 rises the second conduit 8 being in fluid connection to the inlets of the second valve made up of holes 9 e and 9 d applies the pressure within the first chamber 6 to the flap 9 c of the second valve assembly 9 since the flap 9 c is an elastic material with properties of springiness and stiffness the flap remains closed until the pressure rises adequately to overcome the stiffness of the flap 9 c the flap is covering two holes but since the flap covering the second hole 9 e nearest the flap hinge has a spring 9 b over it and hence greater compression against it the first hole furthest from the hinge opens first the opening of the first hole allows some of the air to escape the first chamber 6 as the heel strike initiates the pressure in the first chamber 6 rises until the flap over the first hole opens since the first hole 9 d is small the air flow through it is restricted and the pressure will continue to rise until it overcomes the compression due to the spring 9 b over.