These are actually quite common. I've had three different ones, and currently have one (Altieri?) for my Boosey & Hawkes Imperial Eb. All gig bags are dent-bags, these more than others, but they are fast and conveinient. You can send me yours as a gift
My Pig has a Brasswind Bag; I don't like it because there's no backpack straps, and the protection is so-so. But it came with the horn and I'm a cheapskate.
J.c.S.