the process environment and adversely affect the material or device being polished referring now to fig2 which shows an isometric view of one embodiment of the retaining ring of the present invention retaining ring 201 has a generally annular body having an upper portion 203 a lower portion 204 an inner portion 205 and an outer portion 206 retaining ring 201 may be made of any plastic material known in the art such as polycarbonate polyethylene terpthalate polyethersulphone polyetheretherketone polyphenelynesulfide and others the diameter of retaining ring 201 may be any diameter commonly known in the art the upper portion 203 of retaining ring 201 is configured with a plurality of rigid inserts 202 inserts 202 may be made from stainless steel or other materials either metallic or non metallic that are more rigid than the material of retaining ring 201 in some embodiments inserts 202 have parallel sides and semi circular ends as further described below inserts 202 are positioned in the upper portion 203 of retaining ring 201 such that the upper portion 203 of retaining ring 201 is substantially flat and may be readily affixed to a chemical mechanical polishing carrier head in addition the location of inserts 202 is such that when the retaining ring 201 is affixed to a carrier head inserts 202 do not come into contact with the.