The ‘Koeber’ is a well-preserved example of the violins belonging to Stradivari’s mature period. It bears a label that reads ‘Antonius Stradivarius Cremonensis/Faciebat Anno 1725’ and it appears to have been named after a Mr. Koeber of Hamburg, who owned it at the beginning of the 20th century.
More information: Antonio Stradivari Set 1, Volume 4, Page 96