FIG. 1 is a front perspective view of a cassette for a medical device of our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right-side view thereof;

FIG. 5 is a left-side view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof; and,

FIG. 8 is a rear perspective view thereof.

The broken lines depict portions of the cassette for a medical device that form no part of the claimed design.