They are vessels with a very pronounced belly, decorated with black figure horseheads on both sides.
In contrast to earlier belly amphorae, the painters did not apply a separate frieze on the neck.
The amphorae appear to have had a specific meaning or purpose, remains elusive to modern scholarship.
Should that interpretation be correct, the horses may be connected with Hades, or be symbols of Poseidon in an unusual role as god of the underworld.
Erika Simon proposed that they were typical votive dedications using by the Athenian nobility, who also provided the state's cavalry.