Altra Arrows™ Centrum 246 Premier line sets the mark for quality with industry leading straightness of .001”. Using state-of-the-art measuring equipment to verify arrow shaft and component straightness, along with Altra’s weight-matching process ensures you are getting the most consistent arrows available. Manufactured from a proprietary blend of high-modulus carbon constructed in a way that significantly reduces the spine (stiff axis of an arrow), resulting in easier tuning and increased accuracy. Construction: Proprietary blend of high-modulus carbon ID: .244" Straightness: .001" Weight Tolerance: +\- 1 gr Weight: 300 spine (9.7 gpi), 350 spine (8.5 gpi), 400 spine (8.2 gpi) Quantity: 12-pk Included Components: Standard Aluminum Insert and Nocks