I purchased an ND3 about a month ago. It worked great when the temperature was warmer. When the outside temperature went down, the laser started fading on me. I contacted lasergentics and talked to two different people yesterday. I also got an email from them that said the the best temperature to was from from about 57 to 87 degrees. Email also stated that it would not function fully in cold AND high heat situations. Told me that a FoxPro hunting team was trying them out and that they were putting hand warmers on them. I tried it last night with a small hand warmer and it seemed to work for a while, but then the laser disappeared completely. I will continue to experiment with it. I could probably use it 9 months out of the year here in Texas. I have found the optimum use is to view through your binoculars. You can spot eyes deeper in the woods that you can with a regular spotlight. I usually hunt alone. If I had a buddy that I hunted with consistently, I would get the ND5 instead. Much stronger laser and easier to operate. Not a scope mount, but would use just like a regular spotlight. There is great value in this technology, just not sure they have the bugs worked out. Hope they do.