FIG. 1 is a rear-right-top perspective view of a levelling wedge, showing our new design; FIG. 2 is front-right-top perspective thereof; FIG. 3 is right side elevation view thereof; FIG. 4 is a left side elevation view thereof; FIG. 5 is top plan elevation view thereof; FIG. 6 is a bottom plan view thereof; FIG. 7 is a rear elevation view thereof; and, FIG. 8 is a front elevation view thereof.