Waterless Diffuser

FIG. 1 is an upper, perspective view of a waterless diffuser, according to the 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 plan view thereof; FIG. 7 is a bottom plan view thereof; and, FIG. 8 is a lower, perspective view thereof. The portions shown in broken lines form no part of the claimed design.