Don't waste your money on this mouse. Sure it may be vertical but it is a right royal PITA to use.
It took me 2 days and 6 emails to turn the darn thing on initially. Turns out there is a tiny switch hidden within the label on the bottom. If you didn't know it was there you'd never see it and the instructions that came with it didn't deign to actually point out the location of this elusive switch.
Another annoying feature is that it has its own proprietary charging cable, so don't lose it or you're screwed.
These issues aside the greatest PITA with this mouse is its infuriating habit of turning itself off when not in use. Just wiggle the mouse to wake it up? Oh no, not by a long shot! You must painstakingly find that tiny switch again, switch it, wait at least 5 seconds, then switch it back before the mouse wakes up. If you don't wait the full 5 seconds you're plain out of luck, buddy.
Please don't encourage the perpetuation of this poorly designed mouse and spend your money elsewhere.