The ornamental design for a diffuser, as shown and described.
FIG. 1 is a top perspective view of my diffuser design.
FIG. 2 is a partial enlarged view of the upper right quadrant shown in FIG. 1.
FIG. 3 is a top view of my diffuser design.
FIG. 4 is a partial enlarged top view of the upper right quadrant shown in FIG. 3.
FIG. 5 is a front end view of my diffuser design which is a mirror image of the rear end view.
FIG. 6 is a left end view of my diffuser design which is the mirror image of the right end view; and,
FIG. 7 is a partial cross sectional view along arrows 7-7 shown in FIG. 4.
The dot-dot-dash broken lines show the boundaries of the enlarged partial views, and form no part of the claim. The dot-dash broken lines show the boundaries of the design, and form no part of the claim. The remaining broken lines illustrates portion of the diffuser that form no part of the claimed design.