The couple Supercombos that I have,the handles are a little rounder than most wrenches.
I believe Williams and perhaps some others have a system of interchanging heavy tubular handles and large wrench heads that the handles fit,the wrench head by itself can be used as a very short stout wrench but the tubular handle makes it 2 or 3 feet long?
(edit) I think there is a web site for "Industrial Supply Denver" that has something on it about the Williams wrenches with the interchangeable handle. its
www.industrialsupplydenver.com then click "hand tools for professionals" then "wrenches" then "tubular handle".