The ornamental design for set of crutches, as shown and described.
FIG. 1 is a front elevational view of an embodiment of set of crutches, showing my design;
FIG. 2 is a rear elevational view of the set of crutches;
FIG. 3 is a right side elevational view of a right-hand crutch (see environmental view in FIG. 9 for right-hand and left-hand distinctions) of the set of crutches;
FIG. 4 is a left side elevational view of a right-hand of the set of crutches;
FIG. 5 is a right side elevational view of a left-hand crutch of the set of crutches;
FIG. 6 is a left side elevational view of a left-hand of the set of crutches;
FIG. 7 is a top plan view of the set of crutches;
FIG. 8 is a bottom plan view of the set of crutches; and,
FIG. 9 is a front perspective, environmental view of the set of crutches in use.
The environmental structures shown in FIG. 9 in broken lines form no part of the design of the present invention.