Ravin 400 Grain Lighted Crossbow Arrows, 3-Pack Lighted nock design - easier to find in the field 100% pure carbon construction Ravin-engineered polymer clip-on nocks -the only nocks designed for use on Ravin crossbows High-impact threaded inserts made of brass High-impact aluminum nock bushings 2" high profile offset vanes .003" straightness tolerance