The ornamental design for facepiece strap support, as shown and described.
FIG. 1 is a front perspective view showing the new design for a facepiece strap support.
FIG. 2 is a front view thereof;
FIG. 3 is a back view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof; and,
FIG. 6 is a right side view thereof, the left side view being a mirror image thereof.
The broken line showing of a mask is included for the purpose of illustrating environment and forms no part of the claimed design. The shading is provided to illustrate contour only and is not an indication of surface texture or sheen.
A flaccid mask with straps and a supporting element that force the mask into sealing engagement with the wearer's face in response to force exerted by the straps on the supporting element