Introducing the Five-X Arrow Five-X arrows will score five X's for you. The last one is up to you. Five-X arrows are capable of professional level precision for amazing arrow groups and your success. Five-X is suitable for Recurve and Compound. Internal diameter: 3.15mm. Five-X arrows were developed through the cooperation of Mr. Jang Yongho of the Korean National Team and FIVICS for more the five years. During testing, the perfect inner diameter between the point and shaft was found, which resulted in the best flight stability. In addition, FIVICS has used a new carbon material, MC 46ton Carbon, which give further advantage to the archer for accuracy, while also reinforcing the arrow durability through the epoxy resin. We can tell you that FIVE-X is perfect arrow for competition due to these outstanding reasons. Perfect Grouping Advanced Technology Straightness: +/- 0.001in Weight Tolerance: +/- 0.3 grains Spine Selection Tolerance: +/- 0.01in Shaft Size 350 400 450 500 550 600 650 700 750 800 850 900 1000