These glove liners kept my hands warm when combined with a heat pack and regular gloves, but they were shredded & a huge mess by the time I finished a single day of skiing!  Velcro (which is on most ski coats, boots, & gloves) sticks to these gloves like crazy, pulling out the metallic threads.  Great concept (especially the pockets for the heat packs), but needs some serious improvements in durability.