material:CR-V,S2 Excellent heat treatment,high hardness,high flexiblility 13PCS Impact Driver SetTC-006Bits size:S8x35:PH1,PH2,PH3,PH4,PH2,H5,H6,H8,H9,SL4,SL5,SL6,SL8Bit material:S2,Cr-v,45# are avaliableMetal box 13PCS Impact Driver Set professional tools