This part of ISO 3338 specifies the dimensions of flatted cylindrical shanks for milling cutters, of diameters 6 mm to 20 mm for single-flatted shanks, of 25 mm to 63 mm for double-flatted shanks and of 6 mm to 32 mm for shank with inclined clamping surface. In the case of single-flatted shanks, it is applicable to both single-ended cutters and double-ended cutters, as double-flatted shanks cannot admit single-ended cutters.The dimensions of plain cylindrical shanks and threaded shanks are given in ISO 3338-1 and ISO 3338-3, respectively.The two shank types covered by ISO 3338-1 and this part of ISO 3338 have the same dimensional characteristics (diameters and lengths), but different tolerances on diameters, namely:- h8 for plain cylindrical shanks, commonly used for tools mounted in collets;- h6 for flatted cylindrical shanks, intended to be mounted in chucks and secured with a clamping screw, and requiring an accuracy adjustment.