We claim the ornamental design for a square tube flashing compression ring, as shown and described.
FIG. 1 is a perspective view of a square tube flashing compression ring showing our new design mounted onto a square column with a universal master flash located beneath the square tube flashing compression ring;
FIG. 2 is a perspective view of a square tube flashing compression ring;
FIG. 3 is a front elevation view of FIG. 2;
FIG. 4 is a rear elevation view of FIG. 2;
FIG. 5 is a top plan view of FIG. 2; and,
FIG. 6 is a bottom plan view of FIG. 2.
The broken lines showing a square column onto which the square tube flashing compression ring is mounted and a universal master flash positioned beneath the square tube flashing compression ring in FIG. 1 depict environmental matter and form no part of the claimed design.