I have a friend that actually makes his own light up knocks. it seemed pretty easy when he was telling me about it. I know he gets the majority of the stuff from walmart that he makes them with. Im not sure about the weight but i have seen him shoot about 6 of them on different arrows and they worked every shot. If anyone is interested in knowing how to make your own i can ask him to explain it to me again and i will post a thread on how to make them.