An annular protective ring attachment designed to grip the outer peripheral edge of all compact discs and digital video discs which, when used in combination with said CD or DVD, creates an airfoil. In one aspect, a desired project provides a context for management of a plurality of information elements, each element being in at least one of a plurality of categories. A magnifying rate of an image size of the comparing object projected on an imaging device is calculated. No redundant circuitry is required in the mobile terminal. % further additives or auxiliary agents, wherein the sum is to results as 100%, and a cross-linking component made of polyisocyanates in a NCOOH ratio of 0.