|1st version. horse shoe shaped (open) "c". very rare. I have ever seen only 2 sets(one is mine) .|
|2nd version. horse shoe shaped (open) "c". early-mid 1950s.|
|3rd version. normal(closed) C. mid-late 1950s. soory bad photos. This clips put on my bike.|
|Unusually model. oppisite bird wings!!. No letters on side. I have ever seen only 1(mine).|
|material was changed from STEEL to STENLESS on circa mid 1970s.
The way of bolt and nut became reverse. on circa 1962-63. (Pre) bolt is left and nut is right.(Past) bolt is right and nut is left.