Model Number SS SSP(hard chrome plating processing article, plating thickness t≧3μm) Materials QD51(SUS440C equivalency steel) Surface hardness ≧HRC56 Outer diameter allowance g6, h5 Stock size 3, 4, 5, 6, 8, 10, 12, 13, 15, 16, 20, 25, 30, 35, 40, 50