Even tighter specs for hunters who demand only the best. Buff Tuff® Plus, Diamond Weave, Dual Spine Weight Forward™, with 2" Tiger Blazer® vanes/Tiger wraps, and BullDog™ collar. Straightness: ±.001". Weight tolerance: ±1.0 grains.BullDog™ Nock Collar A Carbon Express® exclusive. Aircraft-grade aluminum collar that fits over the outside of the back end of the shaft, forming a barrier that protects your nock and arrow if it’s struck by another arrow.