RARE Ludwig 1968 COB SUPRAPHONIC Snare Drum Vintage

1968 Ludwig Keystone COB Supraphonic w/crimped bed & 609xxx serial number! A very rare 1968 COB Ludwig Supraphonic snare. It is a chromed brass shell, but is neither the COB Super Ludwig shell of 1958-1962 nor the spun COB 1970-ish shell (with B stamp). It has a crimped snare bed but does not have the curl over on the inner flanges (as did the original welded Super Ludwig shell). It appears to have a welded seam.