Conn cornet mouthpieces use the same basic numbering system as Bach, so compare these mouthpieces to similar Bach models.  The Conn 10-1/2C cornet mouthpiece has a medium shallow cup and a medium wide rim.  The cup diameter is somewhat narrower than 7C.  Often a choice for players who find upper register playing too demanding for 7C.  A frequent choice of players performing many types of popular music.