In a travel measuring instrument, a magnet which is polarized in the movement direction is disposed against a flux conducting part. In structure, the test tee device includes a tee fitting, comprising a tubular section extending between a first and a second opposing openings axially aligned with each other, a third opening communicating with the tubular section of the tee fitting; wherein the tubular section has a inside diameter greater than the first opening inside diameter and the second opening inside diameter. The mechanism also includes an ink cartridge with integral printhead arranged in the media path, and a capping mechanism configured to cap the printhead.