I know lots of folks say that either is fine, but years ago when I started fletching my own arrows, the line of thought that it would be better for the arrow to start spinning away from my riser instead of in to it seemed to make sense. So being a lefty I've been using RW feathers ever since. I've saw so-mo video and the like and many folks who say it don't matter, and maybe it don't, but it makes me feel better about it anyhow, so I shoot RW to get spin away from my riser since Im a lefty.