I was running some align blades on my MX400, they were either 315 or 325 mm, cleared the shorter boom fine... I liked them I think.. (hmmm jury must be out on those) but they are only 15 bucks a set, I figured wipe a couple of these out crashing then I'd look at something else when I get the crash thing out of my system... oh yeah, not carbon fiber but they are re-inforced.. hope this helps..