It is 4.5″ in length for hard to reach areas and should not exceed a maximum of 20,000RPM. Set includes SA-5: Cylindrical Shape 1/2″ x 1″; SC-3: Cylindrical Radius End 3/8″ x 3/4″; SD-3: Ball Shape 3/8″; SF-3: Tree Shaped Radius End 3/8″ x 3/4″; SF-5: Tree Shaped Radius End 1/2″ x 1″.