Nano-Pro™ X-Treme™ is specifically engineered for today's competitive recurve bows. When the difference of success can be that of mere millimeters in FITA, NAA and NFAA long-distance field shooting, the Nano-Pro X-Treme is sure to deliver pinpoint accuracy as a result of its multi-spine construction. With this design, the Nano-Pro X-Treme recovers faster out of the bow while delivering the flattest trajectory and superior down range accuracy. Keeping true to form of the Nano-Pro™ series, it has the smallest diameter of any of our target arrows coupled with the parallel shaft design to virtually eliminate cross-wind drift. Contrary to aluminum core arrows, the Nano series won't take a set (permanent) bend, and consistently hold their initial spine tolerance for several seasons. - Advanced Technology. RedZone Technology - Straightness: ± 0.0015" - Weight Tolerance: ± 1.0 grains - Spine Selection Tolerance: ± 0.002"