I've tried several sizes, including a stock 12", and that is the one I use for trips. Its the most effective but doesn't solve all of the buffeting. Some of the problem is the air coming up under and around the batwing. Hope this saves you a few bucks I tried to stay as low as possible because it looks better imho went 6", 8", then recurves, klockworks. I now use a 8" recurve around town and day trips, and put the 12" stocker on for trips. One word of caution watch where the top of the shield lines up with your line of site. 12" (I think) recurve didn't work for me as you can't see thru the recurve and was even with my line of site.