This is a nice classic Riffault blank that was refaced to a standard classical Alto Clarinet facing.  The rails and window are narrow so there's a good bit of resonance and crispness to the response - which isn't as evident on modern Alto mouthpieces for their wide rails and milktoast rubber.  But this one has the bones of a goodie for sure.  It plays as is; or it offers a nice platform to customize into a personalized mouthpiece made special for you.  Perhaps a more open facing for jazz is your jam?  Or instead, a mellower classical mouthpiece - modified with wider rails is your dictate?  Well this has the stuff to yield to your desire.  
 
Important:  There are no returns on used mouthpieces.  If after you've received it, you just can't get along with it, we'd be happy to exchange it as credit towards the purchase of a BEHN SONO Bb or Bass clarinet mouthpiece, or a BEHN Flagship EPIC, VINTAGE, or EVOKE Bb clarinet mouthpiece.