Constantine caesar, follis of Aquileia

[l.e]

Hi! This is my new purchase: a follis of Aquileia in name of Constantine, caesar under Severus II, RIC 92a...in web I can't find another example of this type...what is its rarity?
thanks! 

[Victor]

They are hard to find. I believe that this type is more scarce than the reverse with prince on horseback-

http://www.lateromanbronzecoinforum.com/index.php?topic=316.0

[l.e]

Thanks, Victor So the coin might be... R2...?