the cap (11) has a sealing cylinder made of an elastic resin or rubber with a base and inner edge at the cylinder opening and an end surface designed so that when the cap is placed on the cylindrical body (1)of the pen the far end of the writing tip (8) butts against the base of the cylinder and comes in such close contact with it that the ink flow region of the tip is hermetically sealed. The inner edge of the cylinder comes into contact with the conical surface of the ink reservoir's (5) forward part or the tip holder middle part. When the cap has been mounted the end of the cylinder can be pressed against the end of the pen body mouth piece so hard that the end region of the air channel opening into the tip is hermetically sealed.
