The 4-FA I've recieved seems to be the original pure crystally mephedrone. Was looking forward to trying 4-FA but won't be complaining too much...
Do you have an EZ tester Cap'n?
I believe someone in this thread tested 4-FA and it turned orange.
You should be able to tell the difference between it and meph because I know you have done plenty of meph in the past.