Review (1/5): Worthless, use other tools instead
I had a terrible time trying to remove my Invisalign braces, and it only got worse after they added attachments. I ordered ThePulTool (thepultool.com), which worked great for six months before breaking. Unfortunately, when I went to order another one, the website says they're out of stock and hope to have new inventory two months ago (no response to my email inquiry, not sure if the company is still around).
In desperation, I ordered both this Retainer Removal Tool and the Outie Tool from Amazon. This one was a complete fiasco. As others have reported, it simply wouldn't grab onto the Invisalign trays, no matter how many different ways I tried to use it. A complete waste of money.
The Outie tool works much better -- not quite as good as ThePulTool, but not bad, and has little trouble grabbing the trays. The "push up" feature for the bottom trays didn't work on one side for me, as I have to grab the tray from the inside of my teeth because of a large attachment in that area, but fortunately the pulling end works fine on the bottom tray as well as the top.
I still like ThePulTool best, particularly since it fits in my case, but until they're available again, I recommend getting the Outie Tool (http://www.amazon.com/Invisible-Braces-Retainer-Removal-Outie/dp/B009HULEKE) rather than wasting your money on this one.