A pair of medium, Thinsulate, battery heated gloves. They’ve only been worn a couple of times.
Each glove has a pouch to hold a battery. The negative end of the battery sits on a spring at the bottom of the pouch (circled in red), the positive end of the battery clips into the “button” on the flap of the pouch. I’m not sure what size battery they use, but it needs to be one where the positive end of the battery fits into the “button” on the glove pouch.