As you have prob already read in the archery section, I got the Lumenok Bolts for my crossbow. You can buy just the nocks for your arrows or bolts, but I bought the complete bolt/nock combo. That way I would have the ones that came with it as spares. They are awesome. It looks just like a tracer flying through the air. I looked at other brands but the lumenok was the brightest that Ive seen so far. The lumenok doesnt require a magnet to activate it like the Tracer nock does. The lumenok stays lit until you wiggle the nock back and forth and brake the connection with the bolt. Just takes a fraction of movement. The Tracer nock will start flashing, I kinda like that feature. Supposed to last 40 hours . Not sure how to replace the battery. Need to figure that out. Will let you know how that works. So far I love them.