This is a Park SW-22.2 Master spoke wrench. It is an investment cast workhorse poured from the best steel, precisely machined, heat treated for hardness, then polished and plated. SW-22 is a four-sided spoke wrench the same size as the SW-2 (red) for .136” (3.45mm) nipples.
The SW-22.2 spoke wrench is sized for spoke nipples with .45 mm (0.136") wrench flats, This size is often found on most department store bikes, as well as many other low-to-midrange bikes — always measure to be sure
