I found this to be useful when I wanted to share the bottle and cage between multiple bikes. I also used it for a long gravel ride to put an extra bottle within easy reach on my top tube. Very flexible.
I needed a way to mount a bottle to my son's bike that didn't have any bottle mounts and this worked great. The smaller bottle and twist design is also easier for him to use than a traditional bottle cage and it easily fits on his little bike. He loves using a bottle now "just like daddy." 100% recommend this for any bike that doesn't have bottle mounts.