This International Standard specifies the dimensions, materials and manufacturing requirements, and designation of collets (of form A or of form B) for tools with cylindrical shanks and their corresponding holders and nuts. For non-standardized clamping devices, such as clamping devices specified in drawings, these holders can be agreed upon between customer and supplier. Form A applies to milling and any other application where a hard collet bore is required, provided that the clamping range of h10 be sufficient. Form B applies for general purposes where an extended clamping range is required.