To prevent a fastening belt or ring from twisting, by forming a ring to penetrate a fastening belt with plastic and forming the sides into a rectangle and the cross section into a flat rectangle.

The inner periphery of this ring 1 is formed into a rectangle, and the cross section of each sides into a quadrangle with plastic. It is especially advantageous to form the cross sections of the long sides 2 and 3 into a rectangle and to make the long sides 2 and 3 to come to the fastening belt overlapping side. The length m of the side 4. of the cross section along the C-C line is made larger than the length n of the side 5. Thus, the touching area of the belt and the ring 1 becomes larger when the fastening belt is penetrated through and the exposing height of the ring deviated to the supporter main body can be reduced. Various kinds of plastic, for instance polyacetal resin, can be used. By this constitution, twist of the belt can be prevented to correctly demonstrate the support function.