Arcadius AE20, 4.09 gr. Bronze weight for solidus (exagium solidi), 
ca. 403-408, Antioch ad Orontem, Syrien. 

DDD NNN GGG, pearl diademed, draped, cuirassed busts facing
of (from left to right) Honorius, Arcadius and Theodosius II.
EXAGIVM SOLIDI, Tyche of Antioch, veiled, seated facing on rock,
holding corn-ears in right hand; river-god Orontes swimming
left at foot. 
RIC-; Cohen-; Bendall Byzantine Weights-.

Extremely rare.

Note: the three busts of the emperors and the reverse legend,
EXAGIVM SOLIDI ("Solidus weight") strongly suggest that this is 
an official coin weight to test gold coins in the mint at 
Antioch ad Orontem in Syria.