Charles Bay MO-M Bb clarinet mouthpiece

Charles Bay Bb clarinet mouthpice. Facing table is smooth, There is a tiny nick at the edge on the left hand side,. The tip rail also has a tiny nick at he right hand corner of the front tip. The side rails are clean without any nicks. The beak has a new mouthpiece patch. Mouthpiece has been cleaned. To the side of the facing is the inscription MO-M for a medium open tip and a medium length facing. Below the MO-M is what appears to be a number 113 and below that is the number G495. I think the 113 is a tip opening measurement. Not sure what the G495 means.