Thank you for viewing. This is a soft case for a tuba. I used it for a YBB641Ⅱ until a few years ago. According to the Yamaha website, the bell size is 419mm and the height is 1018mm, so I think it can be used for tubas up to this size. Soft cases for tubas are quite expensive when new, so I hope to sell it to someone who is looking for one. It has been over 20 years since I purchased it, so there are signs of wear and tear, dirt, and fraying due to aging. It is not a backpack type, but a shoulder strap type. Please check the photos for the condition. I plan to fold it up and ship it in a cardboard box. Thank you for your consideration.