Seller says it is 22mm 2g. The only similar one I can find on Wildwinds is for Caracalla and is a quinarius. Nothing on vcoins. Course I could be completely wrong
Is it a fourree? Looks like it. If so perhaps the forgers didn't pay attention to which reverse it should have or maybe the mismatch was on purpose.
I'm with @TIF on this one. I suspect a fourree, purposely made with a Geta reverse on a Caracalla obverse so the forgers would be able to recognize their own handiwork. The NOBILITAS reverse was only used officially for Geta (except for the quinarius of Caracalla, RIC 162, which reads ANTONINVS PIVS AVG). Such muling is common on fourees of the Severan period.