A glove is a garment covering the hand. Gloves have separate sheaths or openings for each finger and the thumb; if there is an opening but no covering sheath for each finger they are called "fingerless gloves". Fingerless gloves with one large opening rather than individual openings for each finger are sometimes called gauntlets. Gloves which cover the entire hand but do not have separate finger openings or sheaths are called mittens. Mittens are warmer than gloves made of the same material because fingers maintain their warmth better when they are in contact with each other. Reduced surface area reduces heat loss. A hybrid of glove and mitten which contains open-ended sheaths for the four fingers (as in a fingerless glove, but not the thumb) and also an additional compartment encapsulating the four fingers as a mitten would. This compartment can be lifted off the fingers and folded back to allow the individual fingers ease of movement and access while the hand remains covered.