The ornamental design for an undergarment with built-in sacroiliac belt, as shown and described.
FIG. 1 is a front perspective view of an undergarment with built-in sacroiliac belt, showing the new design, with the undergarment with built-in sacroiliac belt shown being worn.
FIG. 2 is a front perspective view of the undergarment with built-in sacroiliac belt seen in FIG. 1, shown alone.
FIG. 3 is a rear perspective view of the undergarment with built-in sacroiliac belt of FIG. 2.
FIG. 4 is a front elevation view of the undergarment with built-in sacroiliac belt of FIG. 2.
FIG. 5 is a rear elevation view of the undergarment with built-in sacroiliac belt of FIG. 2.
FIG. 6 is a first side elevation view of the undergarment with built-in sacroiliac belt of FIG. 2.
FIG. 7 is a second, opposite side elevation view of the undergarment with built-in sacroiliac belt of FIG. 2.
FIG. 8 is a top plan view of the undergarment with built-in sacroiliac belt of FIG. 2; and,
FIG. 9 is a bottom plan view of the undergarment with built-in sacroiliac belt of FIG. 2.
Any broken lines shown are directed to unclaimed portions of the undergarment with built-in sacroiliac belt, and form no part of the claimed design. The wavy dash-dot lines are meant to claim that portion of the surface shown in solid lines and with surface shading up to the wavy dash-dot line. The wavy dash-dot line itself represents a boundary line, which boundary line itself forms no part of the claimed design.