HHIP 3906-0220 - Spring centered tap guide. This spring centered tap guide tool is used to align taps for threading, lathes, mills and jig bores. Point is hardened up to 50-55 HRC. Shank diameter is 1/2". It can also be used with drill chucks to stroke the hardened point for accurate hand tapped threads. The center's body should be gripped in a drill chuck or collet while the hardened point is inserted into the middle of the tapping handle. The stroke of the center will follow the tap assuring straight and accurate hand tapped threads. This is a universal size for all tapping applications.