Further to a previous post about a mythical 4" Bahco Shark, here is a No30 which is labelled 4" but is in fact 6" in length.
A number 30 is well known to be 6", as it should be by the labelling convention where (for the 15 deg heads) No69=4", No70=6", No71=8", etc. In the sharks (or Haj), we had No20 and later No30 as 6" models, then No21=8", No22=10" and No23=12".
Another very interesting example of a mislabel is this early generation 3, 12" No13, which never existed in any catalogue of course. It should be a No73 which would make it a nice but rather ordinary wrench from around 1924. Instead, this one is extremely rare and quite valuable.