The factory wind speed recommendations are only recommendations. What is possible in reality depends both on pilot skill level and the settings used. Different bridles, frames, and line sets will determine the limits. They are no more than a rough guideline. If you must know the original info provided by the manufacturer you can call Revolution kites at 858.679.5785 and ask.
Personally, I feel that the information is totally useless, as wind quality and variability change the range along with each change in the wind, and that can vary greatly several times in the course of a few minutes. To put it simply, the recommended range is beyond a beginner's ability and not even close to what an advanced flyer can do. Where a beginner will have great difficulty flying a standard sail in 5mph wind, the advanced flyer can keep it airborne when there is zero wind. Same problem with top end. Beginner will have no control above 14 or 15mph, but the advanced flyer can push it close to 30mph, and maybe more. Which range would you print on the package, 5-15 or 0-25? Or something in between? The limits are different for each person and, therefore, meaningless.