Philip II AR Antoninianus. 

obv: IMP M IVL PHILIPPVS AVG, radiate, draped & cuirassed bust right 
rev: AEQVITAS AVG, Aequitas standing left with scales & cornucopiae. 

Weight is 4.15 grams, diameter is 21mm.

A variant of RIC 240a, RIC notes "Cohen 1 has rev AEQVITAS AVG - a slip".

That may be so, that Cohen really meant the normal AEQVITAS AVGG, but this
coin matches Cohen's original description, so who can say?  

RIC 240a is rated rare, and there are examples of both kinds in the ANS 
collection.

Image contributed by Docho.