The PileDriver is designed with a high grain per inch ratio for increased kinetic energy and greater penetration. Heavier grain weight allows for exceptional stopping power and helps make the Carbon Express PileDriver remarkably durable and able to withstand the toughest hunting conditions. Compact Predator vanes allow for extra arrow velocity and increased accuracy down-range. Ultimate Penetration - High grain per inch ratio creates increased penetration and exceptional stopping power. Clear coat finish-Provides greater durability and stealth performance on an arrow rest.á For those that choose the fletched arrows, Predator Vanes offer High performance compact design for added arrow velocity and greater accuracy. BulldogÖ Nock Collar - unrelenting strength and durability for nock end impacts.Straightness: ¦ .005" max.