1.R8 collet material:65Mn 2.Hardness:clamping part HRC55-60 elastic part HRC40-45 3.round,square,hex hole 1.the R8 collet material:65Mn2.Hardness:clamping part HRC55-60 elastic part HRC40-453.The R8 collets are used for all kinds of milling machie,whose spindle taper hole is R8,such as X6325,X5325 etc.4. R8 collet