An exemplary printable composition of a liquid or gel suspension of diodes comprises a plurality of diodes, a first solvent andor a viscosity modifier. Also disclosed is the use of a two piece seat or rear panel having a heavier upper portion of heavier material which assists in providing back support while carrying and distributing tension which may be transferred by the tension straps. The disk-holding protrusions are formed on the disk-holding surface of the hub, and are inserted through holes formed in the magnetic disk.