Vintage Conn Standard Steelay Hard Rubber Alto mouthpiece. These old pieces were made from really great rubber and, similar to many mouthpieces of a similar era, feature a large chamber, closed tip and short shank. #5 facings are by far the most common and these were usually included with Conn 6M altos. Notably, Benny Bonnacio, of the Paul Whiteman Orchestra played one of these mouthpieces.
Condition is excellent with very few signs of wear and original facing in excellent condition!