Hoover and Strong carries this, which allows a ring to open for
large knuckles like a Fingerfit or Adjusto Shank. The advantage is
that this can be used on eternity bands, because it is installed
inside the original shank. Has anyone tried one?
On this the hinge and catch protrude slightly on the inside of the
shank, and I wondered how comfortable it is, how easy it is to
install, and how secure the catch is.