The ornamental design for a device for adjusting the straps of a medical facemask, as shown and described.
FIG. 1 is a front perspective view of a device for adjusting the straps of a medical face mask, showing my new design;
FIG. 2 is a rear view thereof;
FIG. 3 is a front 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; and,
FIG. 8 is a front view thereof in an operative mode with a medical face mask.
The broken lines showing an environment for use of the device for adjusting the straps of a medical face mask in the drawings are for illustrative purposes only and form no part of the claimed design.