I am an amateur tuba player in Japan. I needed a gig bag for my Miraphone 88. It fits the instrument perfectly.
Compared to other soft cases (like Supersac, Protec, Gard Bags, etc.), the padding is thicker and sturdier, providing better protection for the instrument. It's also surprisingly lightweight for its durability.
It has two pockets, large and small. The larger one holds sheet music, while the smaller one can store the mouthpiece, oil, etc. If I had to point out one improvement, the pocket for the mouthpiece would be more convenient if it were on the bell cover (incidentally, the previous Miraphone gig bag had it there).