What feature allows chained handcuffs to provide more versatility?

Chained handcuffs feature a swivel eye and link chain, which enhances their versatility significantly. The swivel eye allows for a greater range of motion, enabling the cuffs to adapt to the positioning of the subject's wrists without compromising their security. This design not only accommodates various wrist sizes and angles but also allows for smoother movement, reducing the risk of injury or discomfort for the individual being restrained. Additionally, the link chain provides some flexibility, making it easier for officers to manage different scenarios, whether detaining multiple subjects or adjusting cuffs in cramped spaces.

Other features such as adjustable size, color coding, and a double-locking mechanism serve important functions, but they do not specifically enhance the adaptability and maneuverability of the handcuffs in the same way the swivel eye and link chain do.