I bought Two for last season.

Practiced with them prior to the season opener and one of them kept blinking on and off.
Didn't think much of it, as I only need one arrow at a time, so I just left it in my quiver and used the other.
3-days into the season I arrowed a 6-pointer and the one that I thought was good didn't work on my kill.

Removed the one that winked at me and won't buy anymore!!!