While, at first, this chalk bag may look like it's got some good features; being collapsible, making it easy to fit in your rucksack while also making it stable and not likely to get knocked over. The truth is this is a poorly designed product.
When you unzip the top (which you cannot see in this picture), there is an elasticated 1 inch wide piece of material that is attached around the inside of the bag at the top. This is so you can fit both hands in the bag and shake them about without chalk escaping. This works well-ish. The problem with this feature is apparent after you've collapsed the bag and it's been banging around in your rucksack on your way to the wall. The chalk is shaken up in the bag and finds it's way to the top of the elasticated material, where it will sit until you unzip the bag. Then it will transform into a cloud of chalk that will promptly envelop your face.
Using a zip closure system, as opposed to a draw string, is also a terrible idea. Chalk and zips do not mix well. After a few months you will find that the chalk as caused the zip to stick, you'll end up pulling to hard on the zip and breaking it. You will then have a bag full of chalk and no way to get at it. I speak from experience.
I've owned and used this bag for a few months now. Take it from me, you can get a lot better for the money.