I posted this in S&B but not had much luck so seeing if the chat area can help, please 
DS 14 is after a pair of Levi’s 510 skinny fit jeans. We’ve found the perfect pair online but I’m baffled by the sizing. The options are 2A up to 16A. What does that mean?? I’ve clicked on Size Guide but that doesn’t help confused. Any ideas?
TIA