I used them last year and love them. I had 2 malfunction after I had shot my deer (different deer)-they still let me see where I hit but when I came up on the deer the 2 had no longer been blinking. I sent them back and they replaced them. Now I just opened the new pack and one of them will not activate. Despite this I would sooner use these rather than the lumenoks which I have also had bigger issues with such as splitting down the middle when I shot and costing me my buck in archery. I had to wait until December when it was 15 degrees in order to finally seal the deal on that buck. I also recently tried the make your own as shown on youtube. More of a pain in the a$$ than anything trying to make them perform consistently. I'll just buy more Tracers, they have always treated me well and did what I needed them to do at the time of the shot.