I believe they are talking about offset. It may be a helical fletch that is offset by either 1 or 6 degrees. If I were to buy one of those to fletch my hunting arrows I would get the 6 degree offset myself. The more offset of a helical fletch, the more control but itmay also make the arrow slower at longer ranges so, if speed is important to you that may be a consideration. I like maximum arrow control myself and my max range for deer is only 25yds so speed would not be an issue.