A head slider for a hard disk drive is disclosed. The results of which is the possession of a single ticket that can be used to prove authenticity of multiple authentication principals to one or more online services. Cepstral vectors are computed from the transformed spectra. Fuel cell technology is also implemented. The disk and balancing ring may be mounted on a disk balancing system to determine a mass center and trim the protuberances, accordingly, to establish adjust the rotational center of the diskbalance ring to be coincident with the mass center. Both the frame member and the loupe assembly are provided with complementary magnetic mounting means, whereby the loupe or magnification system is releasably mountable to the frame member.