Meh.......I bought a couple a few years back, they broke pretty quickly. Really didn't increase speed much either. Probably be fine if you have rims with a shorter height, and tires that aren't super-hard to get on. On a Rhyno Lite/Velociraptor setup, you might get three tube repairs out of them.
I bought one way back when they first came out. Found it lacking, used it a few times and just collects dust now. Just amazes me thinking that was the launch of Crank Bros (I believe it was at least...did I miss another product before it?).
"...the people get the government they deserve..." suum quique