His listing is for a vintage Otto Link "Reso Chamber" mouthpiece for alto saxophone. This model was produced in New York in the 1940's, concurrently with the Tone Master. It has a large round chamber and scooped inner side walls. The tip opening is 4 (marked on the table), and it measures. This piece is in excellent physical condition.
The tip, table, and rails are all perfectly smooth. It has never been refaced, or altered in any way. The beak is free of tooth indentations. The rubber material is a bit faded from age and light exposure, and the markings are a bit hard to make out, but they are there. Interestingly, there is no serial number on it.
Maybe they stopped doing that at the end of the run of this model. The item "VINTAGE OTTO LINK RESO CHAMBER ALTO SAXOPHONE MOUTHPIECE ORIGINAL 4 =.070" is in sale since Friday, January 4, 2019. This item is in the category "Musical Instruments & Gear\Wind & Woodwind\Parts & Accessories\Mouthpieces". The seller is "greatlakeswinds" and is located in Milwaukee, Wisconsin. This item can be shipped worldwide.