Bought for my wife with Raynauld's Disease. She has been using them for ~3 weeks so long term review not possible yet. Have tried many solutions over the years with reusable hot packs inside down mittens being the most effective for the past 10-15 years. Unfortunately, boiling the packs to reset them is a bit tiresome and her thumbs would still get cold. The Zanier gloves have kept her hands warm while walking the dogs at ~10 degree F, albeit on the on the high setting for the duration of the walk. The thumb is heated and is doing a better job than the previous hot pack solution. When I tried them, I felt immediate heat and suspect they would work well on lower settings for a person with normal circulation. These gloves were the cheapest of the expensive models offered and also on-sale which affected my purchase decision. They are still crazy expensive to the lay person for a pair of gloves and far costlier than our previous solution, so what we are really buying is convenience. If they are still performing well a year from now and the batteries have a long life, then it will be a win.