The Pentachalkon denomination
The pentachalkon was an ancient Greek and Eastern bronze denomination worth 5 chalkoi.

Since the numbe of chalkons to an obol varied across regions a general weight is impossible to define, except that it weighed five chalkoi from the region it was struck in..
Pentachalkon

(1) Azes I 57-35 BC
Obverse: ΒΑΣΙΛΕΩΣ ΒΑΣΙΛΕΩΝ ΜΕΓΑΛΟΥ / ΑZΟΥ King on camel right, holding ankus
Reverse: Zebu bull (or yak) standing right; monogram below
Ref: Mitchiner 2325 or 2326