An optical spectroscopy tool is provided. Each fuel cell unit includes an electrode assembly having electrodes and an electrolyte, a pair of separators, and gas sealing members. In the stow-away position, the computer case hangs from a pair of guide rails with the cable connectors facing up, for easy installation. During computer system start up the System Enabler file modifies the generic operating system software for optimum operation with the particular computer hardware system. A latching member is mounted on the upright interior pit wall and has a plurality of vertically spaced teeth that face the catch member. The sleeve and the snap-clip mechanism can be selectively configured to accommodate chainsaw bars of different shapes and dimensions and the spacing of whose guide bar adjustment nuts varies.