How Everything Is Made on Instagram: "Handcuffs are mechanical restraints designed to restrict a person’s wrist movement by securing both wrists close together. Each cuff uses a ratcheting arm with small teeth that tighten in one direction and lock in place. Once closed, those teeth catch on a spring-loaded pawl, preventing the cuff from loosening without a key. Most handcuffs also include a double-lock setting, which stops the cuffs from tightening any further and helps prevent injury during us