Assures that the press pin is held perpendicular to the pressing force.
This will hold round items up to 1/2" diameter. It would also hold tri-lobe items as well. The chuck with the magnetic back plate is 2.9" high. The distance from the back plate to the top of the internal backing pin is 1.785". So, if you use a 2" press out pin overall tool length will be (1.785" + 2.0") = 3.785".