The present invention provides a metal complex containing a cation represented by 22242+ in the aforementioned formula, MII is PtII or PdII, MI is H+, AuI, AgI, CuI, HgI, TlI or PbI, and LC and LB are ligands. In one embodiment, a kit of superior or inferior prostheses is provided, in which the prostheses have at least two dimensions that vary among members of the kit independently of each other. A slide mechanism includes a support part guided by the guide rail and a pair of pinion supports. Thereafter, the polarization-changed light and the polarization-maintained light easily may be recombined in an entendue-maintaining manner. If the measure exceeds the second threshold, then a more-extreme second set of actions is taken. The system can be customized by subscribers for all or specific contacts.