DetailsSpecifically designed for use with the Excalibur Matrix 355 and 380 series crossbows. Excalibur teamed up with Easton to develop the Diablo carbon arrow. Spine for blistering speed, they have a heavier front insert to increase front of center weight for unparalleled accuracy. Features a fatback insert which means no need for a nock that gives you more contact with the string. Arrows are 18 long and fletched with 2" vanes for speed.