I have not used one but I noticed they have a bunch of them in the "bargain cave" at Cabelas in Dundee, MI. This is where they sell all the items that have been returned or damaged. I asked the man there why they have so many and if they work. He said they really only work well at very low temperatures below freezing and then only just after the animal is down. I suspect that many were disapointed with their usefulness, and hence all the returns.