I found the XLAB after tiring of other seat cages that ejected my bottles like depth charges when I hit dips going through intersections. Riding in Arizona, we can easily drink 60 ounces of water on a 30 mile ride in summer, and this is a great way to take an extra bottle, including insulated Camelbak Podium 21s, which fit. I like the tight fit to keep my extra bottle in place over bumps. Regular uninsulated bottles fit a little less snugly - but still pretty snug. Relatively slimmer insulated bottles like the Podium 21 is very tight, but work. I also have a Speedfil 40 oz. tank system for primary drinking while pedaling. I use the XLAB Aero to carry Heed electrolyte replacement to drink at stoplights, or on a shorter/hotter ride, just water to dump on my head. The seat bag part of this rig holds a surprising amount of stuff, although an extra tube is very tight if you have many other tools. The hardware is very sturdy and adjusts to give you a range of angle and depth options. Once on, it's solid as a rock. Nothing rattling or wobbling. Assembly seemed intuitive. If I had one gripe (let's call it a suggestion, more accurately), is that a tab or loop for a rear light would be a nice addition. For technical comparison, I have this on a 54" Cervelo S1 (aero seat post), with a Cobb Delta M saddle.
