General Purpose HD Swage Block:
This is a good old heavy duty general purpose design block.
What makes it "heavy duty" is the solidity of the block and lack of weak corners.
It is considered general purpose due to the center depression and the extra large curve on the top.
This is an old and fairly primitive block.
The top curve was not drawn with a compass but with a slender bent board which produces a catenary rather than a true radius.
Photographed in a Pennsylvania antique shop by Jock Dempsey