A distributed resonator laser system using retro-reflecting elements, in which spatially separated retroreflecting elements define respectively a power transmitting and a power receiving unit. The vessel running data generating unit generates vessel running data of a vessel. The license package includes a first layer and a second layer separately encrypted therein. The present inventions are particularly adaptable to hollow, metal bats; and provision is made for venting the knob of the bat when it is welded in place so hot gases will not be forced into, and reduce the integrity of, the weld. The SiO2 is thereby located away from the ABS surface and the induction coil is subsequently fabricated within the SiO2 material. Further, a slope adjuster is provided to adjust the angle of the stop members relative to the upper connect rods for making three modes of exercise.