Biberphon

German label that released "unbreakable records" (Unzernbrechliche Schallplatten). The records were made of a celluloid core covered with acetylene and cellulose combined with camphor. They're flexible, but much thicker than flexi-discs from later days. They were only active in 1930/1931. For their production they used matrices from Kalliope, as well as from US labels Banner, Perfect (3).