David Sundewrote a review of e*thirteen components Extended Range Cog on September 4, 2015
Having run 1x10 and 1x11, I almost prefer a 1x10 Shimano upgrade over the 1x11 for a few simple reasons. Cost is significantly less if you're already running a 10 speed rear derailleur and shifter (XT or XTR is best here). 11 speed will require a new shifter, derailleur, cassette and potentially a hub driver. Depending on the riding you do, it is a bit quicker to go from top to bottom in 10 gears than 11 with the same overall ratio as the XTR 11sp. You only miss one gear in the mid range in comparison. Shifting is still smooth, installation is pretty simple and set up easy with the included B-Screw to give your derailleur clearance. Other upgrades to make this run even better would be a Radr cage from OneUp and a race face narrow wide chain ring for your crank. Overall, awesome product and the best bang for the buck when upgrading your bike.