Heavy grain weight of the Carbon Express PileDriver Crossbolts creates maximum kinetic energy and greater knock-down power. Advanced construction ensures spine consistency for greater accuracy. The composite material is extremely durable at impact for exceptional reliability and repeat performance. Real Straightness Precision sorted for straightness to +/- 0.004" for repeat maximum consistency (maximum measurement, not an average). Bone Crushing Penetration - Engineered for maximum kinetic energy and greater knock down power. Laser Match Set - Pack sets are sorted and matched by spine and weight for best-in-class consistency. Spine sorting tolerance +/- .0025" and weight sorting tolerance +/- 2.0 grains. +/- .002 Real Straightness - Laser checked for straightness to remarkable 1/10000 of an inch. Universal Nock System includes inserted moon nocks plus C-Nocks compatible with older crossbows that use a Capture nock. 4" Fusion Vanes. Available in 6-packs of 20" and 22" or a 3-pack of 20" lighted nocks.