This is the same as my wifes, BUT, there is a newer or different model out there that doesn't have the rubberband neck holder, (which quickly wore out and broke on the first tour). The other model has a spring loaded hook that holds the neck of the bottle, but I don't remember were i've seen it. It looked like a much beter design.
She now uses a large/thick plastic tie that fits just over the neck and it works real good, just flip the plastic tie up and pull the bottle.