Don't be fooled, it's not for mouse (only), it can do much more!
Screwed to the laptop stand, in my case, it's the perfect place for the RME Fireface UCX interface when I'm playing instruments, or the RME ADI-2 PRO when I'm DJ-ing (or the Babyface Pro, if I came as I was). Can be placed right where it's needed, near your hands or out of the way, and always locks full tight when you need it, or it lets itself be moved in and out of reach if you so wish.
Worth every cent, wouldn't do without it even if I had to run just a presentation without a mouse: laser-pointer, telephone with countdown screen, PSU with a neatly coiled AC cable to avoid the usual copper spaghetti salad... grab one on your way out, and you'll wonder (like I did) why on earth I made without it for such a long time!.