Bowhunterportugal, yes they will be difficult to load into the wrong clamp. The feathers have a natural curve and if that curve is counter to the helical clamp you're using, you'll have to fight them to get them into the clamp. You can do it, but why? Left wing - left helical. Right wing - right helical. If you're fletching straight, either wing will work, but again, don't mix left and right wing feathers on the same arrow. You can, however, mix a dozen arrows, some left helical, some right helical, and you probably won't be able to tell which is which by shooting/acuracy.