I claim the ornamental design for a mobile phone wrist band, as shown and described.
FIG. 1 is a top view of the mobile phone wrist band.
FIG. 2 is a bottom view of the claimed design.
FIG. 3 is a left side view of the claimed design.
FIG. 4 is a right side view of the claimed design.
FIG. 5 is a front view of the claimed design.
FIG. 6 is a rear view of the claimed design.
FIG. 7 is a perspective view of the claimed design; and,
FIG. 8 is a perspective view of the claimed design in use as attached to an appendage.
The broken lines appearing in FIG. 8 of an appendage, cell phone and bicycle handlebar are environmental matter and form no part of the claimed design.