The ornamental design for an “elastic element,” as shown and described.
FIG. 1 is a perspective view of an elastic element showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof;
FIG. 8 is a perspective view viewed from another visual angle thereof; and,
FIG. 9 is a referential view showing my new design as it would appear when in use.
The broken line showing of a slider in FIG. 9 is included for the purpose of illustrating environmental matter and forms no part of the claimed design.