The ornamental design for a controller for shoulderstrap for bags, as shown and described.
FIG. 1 is a perspective view of a controller for shoulder strap for bags;
FIG. 2 is a front view of the controller for shoulder strap for bags of FIG. 1;
FIG. 3 is a rear view of the controller for shoulder strap for bags of FIG. 1;
FIG. 4 is a left side view of the controller for shoulder strap for bags of FIG. 1;
FIG. 5 is a right side view of the controller for shoulder strap for bags of FIG. 1;
FIG. 6 is a top view of the controller for shoulder strap for bags of FIG. 1;
FIG. 7 is a bottom view of the controller for shoulder strap for bags of FIG. 1; and,
FIG. 8 shows a perspective view of the controller for shoulder strap for bags of FIG. 1 holding a belt connected by being placed on one of backpack straps.
The broken lines illustrate environment and form no part of the claimed design.