HSK is a newer tool holder standard that comes from a German acronym for “hollow taper shank.” The design of the HSK lacks a retention knob (pull stud), and as the name suggests, features a hollow shank. They are designed for high-speed machining and are growing in popularity as a result of their precision performance; they offer better radial stiffness (much higher than a CAT, BT, or SK tool holder) and high-speed precision. These HSK 63F tool holder chucks offer these advantages and are popular for woodworking applications.