Hammond Design Trombone Mouthpiece 13ML Rim & Inner Gold Plated Rim Diameter: 25.4mm Throat Diameter: Approximately 7.1mm Rim: Semi-flat Cup: Deep According to Hammond Design's website, this is equivalent to a Bach 6 1/2AL or a Schilke 50. In my personal opinion, it feels like a cross between a 6 1/2AL and a 5GS. It's compact, yet doesn't feel cramped, and has a bright tone with a wide dynamic range that's easy to control. New Price: ¥37,400 (Silver Plated) This one cost nearly ¥50,000 due to the added gold plating.