This particular type of Eastern Celtic tetradrachm was probably minted somewhere in Pannonia during the 2nd or possibly the first Century BC.
Denomination : Bronze tetradrachm. These are normally refered to as billon, but the alloy is so low in silver that by this point I think it is better to refer to them as bronze rather than billon.
Size : 20.1 x 21.2 mm. Weight : 8.05 grams.
Reference : These are fairly common, yet I have no yet found a reference for them.
Grade : VF and nice for this issue.
Obverse : Head of Zeus right. The style is very crude, but you can clearly make out the nose, beard and hair.
Reverse : Boy on horse back left.