I love this heat shoes! But as always I need a lot of warmth, I need to do it 2-3 times in the microwave before my feet are warm. Unfortunately, my Microwave the prescribed 800Watt not, so they have to clean up at 1000Watt. I think that something eaten on the shelf, but 2 winter they make loose with. This pair now also does not stink like my last, but they are after heating also slightly moist. What does not do anything for warm feet!