This is a vintage metal Otto Link Super Tone Master mouthpiece for the alto saxophone, serial number 15. This piece is from the ealier Florida vintage days, with double lined shank. It has been professionally opened to .090" and is a great playing mouthpiece. This Florida vintage "STM" has a nice warm, dark sound, and speaks incredibly well in the lower register. It also has very smooth sound in the upper register. These alto mouthpieces were made famous by Sonny Stitt.