Willie's K2 Type R Bass Trombone Mouthpiece 1G Rim Inner Gold Plated A custom-made item not in the regular lineup. The circumstances of its creation are unknown, and the detailed specifications are unclear, but it is presumed to be a custom-made 1G size for bass trombone, based on a Bach tenor bass mouthpiece, from the Willie's K2 series. *Used item, tried a few times after purchase. There are no noticeable scratches or accident history, and it is in a beautiful condition for a used item. There are slight shank scratches from use, but please check the photos for details. My personal playing impression is generally the same feeling as a Bach 1G, with the impression that the sound is clearer. Why not give it a try?