Founded by Georg Kellermann in 1910, Nuremberg, Germany. Kellerman manufactures clockwork tin motorcycles and other penny toys under the trademark: C.K.O.
Son Willy took over the firm following the death of his father in 1931. From 1954 to 1979, CKO made a series of 1/35th-scale toys called the "Rollo Series", which are popular with today's collectors.
It ceased in 1979 but a Chinese manufacturer in the 1990's has reissued some of its toy vehicles.
What's it worth? Take a look at this Cko price guide: sold listings for a value indication.