A knitted article that includes a top portion, a bottom portion and a seam is disclosed. The optical portion periodically has a pattern, which is formed by pattern portions mutually adjacent in a second direction orthogonal to the first direction and mutually shifted in the first direction, in the second direction with a second period of t. Metallic compression members may be swaged to compress the skirt against the shaft, and thus provide a uniform seal between the balloon skirt and the catheter shaft. When the air control solenoid is engaged, compressed air is provided to the air burst nozzle.