The flexibility is also used to provide accurate axial location. An HSK toolholder has both a tapered shank, and a flange with a mating surface. The shank is short (about half as long as other machine tapers), with a shallow taper (a ratio of 1:10), and slightly too large to allow the flange to seat fully in the socket. The thin walls, short shank and shallow taper provide a large opening in the back of the tool. An expanding collet fits in there, and mates with 30° chamfer inside the shank. As the drawbar retracts, it expands the collet and pulls the shank back into the socket, compressing the shank until the flange seats against the front of the spindle. This provides a stiff, repeatable connection because it utilizes the centrifugal force inside the spindle. As centrifugal forces increase the expanding collet within the HSK forces the walls of the toolholder shank to stay in contact with the spindle wall.