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At the lower end (grip) of pen outer tubes replaced by collapsible plastic/rubber.

The upper end (back) of inner tube holes are provided

A valve/ movable part is inside the inner tube as shown, it also has a point of attachment of refill.

Between the two tube a liquid is filled.

When the pen is gripped for writing Grip is pushed inside so liquid moves inside the inner tube through hole , this pushes the valve forward along with refill

                        The pen will not need spring when the plastic of grip is hard  enough to provide suction.

• When the grip is released grip will come back to its original position and liquid will move from inner tube to the gap between tubes, this will move refill inside the pen.