Carbon Express Predator AIR 4mm Arrows Shafts 300 Spine 12 Pieces Black. Each shaft is produced with 360-degree spine consistency to promote uniform flex and repeatable launch behavior from arrow to arrow. Straightness is held to +/- 0.025 inch max with an average straightness of +/- 0.002 inch and weight tolerance is +/- 2.0 grains. Components 4mm aluminum 50-grain outserts. Specifications for Carbon Express Predator AIR 4mm Arrows Shafts: Manufacturer: Carbon Express Color: Black Fabric/Material: Carbon Quantity: 12 Diameter: 4 mm Features of Carbon Express Predator AIR 4mm Shafts: 4mm micro-diameter shaft profile 360-degree spine consistency Straightness:+/-0.025 inch max Average straightness:+/-0.002 inch Weight tolerance:+/-2.0 grains Components: 4mm aluminum 50-grain outserts Available in 300 350 400 Package Contents: Carbon Express Predator AIR 4mm Arrows Shafts Carbon Express CX05767: Predator AIR 4mm Arrows Shafts 300 Spine 12 Pieces Black