Simple wrist shackles. These cuffs lock when a hex-screw is applied to hold the two halves together. The shackles themselves are made from 3/8" round stock with a welded rivit acting as the pivot hinge. Connecting the two shackles is a 10" chain with a ring in the middle (allowing the passage of a chain through multiple such shackles to form a gang chain. Sizing is such that a S will fit most wrists snuggly and a M loosely (though not loose enough to be removed.) An L would stay on only the largest wrists.