If you own a Microtubes 900, and you're an active musician, you kinda need this bag. The Microtubes has a rather specific form factor, which makes it difficult to schlep about. It being a rather expensive piece of equipment, you don't want to toss it in a bag either.
This bag is specially made for the Microtubes, and you can tell. Obviously it fits perfectly, and the material, the finish, the straps, the zippers; it all says high quality. But this is reflected in the price as well.
All in all, I feel this should have been included when you buy a Microtubes 900, and charging EUR 100,- for it separately is not really cool, but I will still recommend it.