Excalibur teamed up with the arrow experts at Easton to develop the Diablo crossbow bolt. Designed specifically for the Matrix series of crossbows, these bolts are spined for maximum speed. The heavy insert increases front of center weight for superior accuracy and penetration. The flat-back inserts on these bolts eliminate the need for a nock, giving you more reliable string contact. Note: Arrow nock color and fletching color on arrows is selected at the factory. All arrows within a single pack will be the same fletching and nock color combination. Depending on production runs colors may vary.