Steel Shot Specs S70, S110, S170, S230, S280, S330, S390, S460, S550, S660, S780, S930 Durability 2000~2800times Chemical Compsition :C (0.70～1.20) , Mn (0.35～1.20) , Si(0.40-1.20) , S (0.05max) P (0.05max) Hardness Normal:40ᦉ ...Read More