There are several situations where signs may not always be a feasible option. For instance, using signs to mark parking spaces or poles in warehouses, shop floors, etc., that often have more than one or two entities to be identified may prove to be unnecessarily expensive and cumbersome. Adhesive individual letters and numbers are a convenient way to achieve systematic organization in a number of ways and places.  These can be mixed and matched as required, used to achieve sequential marking, color coding, etc., without burning a big hole in the pocket. Installing these is also extremely quick and convenient, given the adhesive backing that these come with.