Istros AR hemiobol, 8.2 mm, 0.53 g, circa 280-255 BC. 

Two facing male heads, the right inverted.
ISTRIH, sea-eagle standing left on dolphin, Delta beneath dolphin. 

Unpublished as hemiobol. Agora 101, 51.

With permission of Agora Auctions auction 101, Lot 51, July 2021.