The glove plays off this reaction. We have other AVAs, but the palms are the most prominent, so that, of course, is where the glove does its work. The setup sounds simple: it doesn't look like much more than a plastic glove hooked up to a portable cooler. But when a hand goes into the glove it creates a slight vacuum, which causes the veins in the palm to expand and draw blood through the AVAs. A lining of chilly water in the glove cools off the blood as it starts to circulate throughout the body.