This is a BestBrass mouthpiece for large-bore trombones. I used it once in a concert and also for cheering at a baseball game with a brass band. I purchased it new from a musical instrument store several years ago. The product itself is a BestBrass GP for large-bore trombones, featuring the manufacturer's unique Groove processing. According to the website, the size is equivalent to a Bach 6-1/2AL. The playing experience offers a remarkably bright tone and an outstanding feel with excellent projection, producing a very powerful sound. The air you blow in is converted into sound effectively, making it suitable for jazz, brass bands, outdoor performances, and even concert band settings. There are some minor scratches and age-related dirt from use, but they are barely noticeable at a glance. There are no issues affecting performance. It comes with the original box and bag, and I will pack it in bubble wrap for shipping.