I think that is earlier (before Ludwig was importing drums) due to the muffler being present. They haven't been putting mufflers on drums as standard equipment for quite a while. The Rockers do seem to use a different hoop than regular Ludwigs but they were still being made in Chicago (perhaps the hoops were imported for the cheaper lines).
Or...Maybe not...I certainly don't know about every cheaper snare Ludwig has made in the past 30 years, but if it has a B/O badge then you have one of the drums I was thinking about and they are American made and can sound very good.