The relatively thin faces (20x6mm & 20x5mm) of the HMR-3 allow you to raise and planish in narrow spaces.  Raising hammers are used to raise sheet metal into a bowl against a stake or other surface without thinning the metal, but you can also use them to planish concave curves in metal such as small cylinders. Fretz casts their hammer heads from 420 stainless steel and tool hardens them to 50 HRC. The handles are made from oiled hardwood shaped and weighted to balance the head perfectly.  Made in Vietnam.