Yamaha SL48L Mouthpiece Trombone for The Standard Series Large Shank

Yamaha Model 48. Well-balanced rim and cup with a fairly narrow backbore. Similar to a Bach 6-1/2AL or a Denis Wick 6BL. Inner Diameter = 25.25mm. Contour = standard. Thickness = standard. Cut Depth = standard. Throat = 6.62mm. Backbone = semi-narrow.