US D282541 S
FIG. 1 is a front elevational view of a main key telephone system casing showing my new design;
FIG. 2 is a rear elevational view;
FIG. 3 is a left side elevational view;
FIG. 4 is a right side elevational view;
FIG. 5 is a top plan view;
FIG. 6 is a bottom plan view; and
FIG. 7 is a left side and front perspective view thereof.