I was on you tube a few days and saw these went home and made three of them they work great and they are about a third the price of a lumenock. http://www.youtube.com/results? search_query=lighted+nock&search=Search
I think it looks like an accident waiting to happen. I would think that drilling through the knock would weaken it. Last summer I had an arrow explode on me and I believe that it was due to a cracked knock. About 2 months I notices a crack in another knock. It might just be me but I wouldnt alter a knock in anyway. That is why I think it is an accident waiting to happen.
I was at Gander mountain last night and looked for those battery/lights for bobbers and they didn't have them. Who carries those things ? I think I'm going to make one of those up for kicks and play around with it.
I use Easton Axis for hunting. I'm also wondering if the battery/light fits into an Axis shaft. Those are really small diameter...