Abstract: Golf putter heads have a one-piece heat treated high hardness stainless steel body having an upstanding wall with a striking face, and directly behind it, a downwardly disposed thin unbounded through-cavity to provide distinct repeatable audible feedback. The putter heads can have a centrally located rearwardly extending mass of body material in the form of an integral spherical mound to provide balance and a high moment of inertia. Methods of making the putter heads are disclosed.