Carbon Express Predator AIR Arrows 350 6 pk. Single spine, 100 percent carbon construction;Straightness: +/- .0025?;Weight tolerance: +/- 2 grains;Inner Diameter: .244?;Standard length: 32?;Fletching: Q2I Fusion XII Shield Vanes;Includes stainless-steel inserts;Size (Spine) GPI: 300 (.305?) 8.6;Size (Spine) GPI: 350 (.304?) 8.0;Size (Spine) GPI: 400 (.333?) 7.2;Size (Spine) GPI: 500 (.391?) 6.2