The next generation of tags was crescent shaped with a blue field and black writing. These were introduced in the mid-1950s and were used on both the individual coffee can type filters and the new “Three-in-One” type air cleaners which had a single long housing that contained all three individual filter elements. These tags had a chord length between the rivets of 51mm. Early F.I.S.P.A blue and black crescent shaped tags with the 51mm chord length.
This is a blue aluminum tag, “AEC 103A”, (40x100mm) used on the Dinoplex units on the Daytona coupes. It warns against loosening the battery cables when the engine is running. Blue AEC 103 A Dinoplex tag for Dayonas