SFU1610 600mm Ball Screw Set : 1 pc ball screw RM1610 600mm+1pc SFU1610 ball nut cnc part standard end machined for BK/BF12 sfu1610 200mm ball screw set 1 pc ball screw rm1610 200mm 1pc sfu1610 ball nut cnc part standard end machined for bk bf12