The heads available in the Bowers and Fowler XT heads line cover all of your bore measurement needs. Each specific head comes with a particular purpose to which it can be applied. The types of heads available include: thread, groove, internal spline, external spline, spherical, deep hole pneumatic, irregular spacing, right angled adaptor, gun barrel head, blind bore, slot width (large), and slot width (small). Additionally, Fowler and Bowers took the time to answer the challenge of measuring dovetail slots and turbine grooves. If you work with the internal measurement of surface or subsea valve cavity-seat pockets, then look no further because they covered that too.