SLOKER TENOR TROMBONE 1A Gold Plated Finish Mouthpiece for Large Bore Trombone Inner Rim Diameter: 25.5mm Comparable to a 6 1/2 or 5GS Supervised by Blanimir Slokar This older model in good condition with gold plating is rare. It's a one-piece design, not the current rim-change type. Although designed for tenor-bass trombones, it can of course be used on tenor trombones if they have a large bore. The condition is considered to be quite good. I understand there are very slight scratches on the shank from being test-played a few times after purchase.