Compare Semroc Centering Ring Plywood ST-7 to ST-9 x 0.25"(2pk)(same as TR-9, CR-79) SEM-CR-7-9P Semroc Centering Ring Plywood ST-7 to ST-9 x 0.25"(2pk)(same as TR-9, TS-9, CR-79) SEM-CR-7-9P… Now: $1.39 Add to Cart