Bondage mittens (sometimes called bondage mitts) are pouch-like coverings that fasten securely around the wrists, holding the hands in closed fists or palms flat. They are often used in BDSM play. Unlike mittens for cold-weather use, bondage mittens are tubes or bags without a separate thumb and are typically made of leather or some other stiff material to prevent the wearer from grasping through the material of the mittens. Some mittens hold the hands flat in a sandwich of stiff material; others trap the hands in balled fists. Both kinds often include a ring at the end with which to anchor the mitten to other restraints.