Speedpro Speed Pro Pro-Series Plasma-Moly File Fit Ring 4.675" +.005" Bore, .043", .043", 3.00mm, Low Tension (SPR20106 005)4. 675" + . 005" MOLY RINGS SET 4. 675" +. 005" Bore, . 043", . 043", 3. 00mm, Low Tension Part Number: SPR20106 005 Pro Series Plasma Moly File Fit Ring Sets Pro Series ring sets are designed for serious racing, with several features that maximize horsepower potential. These rings are not recommended for street use! Most Pro Series sets incorporate reduced radial wall thickness rings for lower tension and enhanced sealing. They also use a very low