Part of Smartphone Holder

FIG. 1 is a front perspective view of a part of smartphone holder, showing my new design; FIG. 2 is a front view thereof; FIG. 3 is a rear 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 perspective view showing the part of smartphone holder in use in an exemplary environment. The broken lines in the drawings depict portions of the part of smartphone holder that form no part of the claimed design. The broken lines showing a smartphone holder and strap in FIG. 8 depict environment that forms no part of the claimed design.