Watch List notes:

Marcus Aurelius. A.D. 161-180. AE sestertius (33.2 mm, 25.06 g, 12 h). Rome mint, struck A.D. 166. M AVREL ANTONINVS AVG ARM PARTH MAX, laureate head right / TR POT XX IMP IIII COS III, S-C, Victory standing right, holding palm and shield inscribed VIC/ PAR in two lines set on palm tree. RIC 931 (M. Aurelius); BMCRE 1289. aVF, brown patina, small flan crack. 

This reverse marks the victory over the Parthians, adding Mesopotamia to the Roman empire.