A magnetic tape cartridge includes a cartridge casing formed by upper and lower casing halves connected together, and a single reel around which a magnetic tape with a leader pin fixed to the leading end of the magnetic tape is wound and which is contained in the cartridge casing for rotation. A disclosed semiconductor device includes a semiconductor substrate, a gate on the semiconductor substrate, spacers on sidewalls of the gate, an epitaxial layer on the semiconductor substrate, sourcedrain regions within the semiconductor substrate below the epitaxial layer, and low doping concentration regions within the semiconductor below the spacers. The golf club head is tuned by changing the viscosity of the rheological fluid. The first end is secured to an associated pivot while the second end is movable along the arcuate path.