Spanner wrench is designed to open jam nuts, plated malleable iron.
Its long supported grip is used to drive retained rings, threaded collars and
spanner headed screws with the support of strong hooks or pins.
Check out the Spanner wrench tool catalogue for more sizes and varieties
like: adjustable spanners, from the taper locking spanners which needed a
hammer to set the movable jaw to the size of the nut.