Thumbcuffs are a metal restraining device that lock thumbs in proximity to each other. Thumbcuffs were originally intended for use by detectives, narcotics officers and off-duty policemen, their size allowing them to be carried in the pocket. Most are rigid devices, while some used in Asian countries are chain-linked, like miniature handcuffs. Thumbcuffs are rarely used due to an increased possibility of injury, most commonly by tight cuffs blocking

blood circulation The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...

. Handcuffs are usually used instead. Thumbcuffs may also be used as improvised ''toecuffs'' by locking the

big toe Toes are the digits (fingers) of the foot of a tetrapod. Animal species such as cats that walk on their toes are described as being '' digitigrade''. Humans, and other animals that walk on the soles of their feet, are described as being '' pl ...

s in proximity to each other. Thumbcuffs with double locks have a lockspring which, when engaged, usually using the top of the key, stops the thumbcuff from ratcheting tighter and prevents the subject from tightening them, possibly causing injury. Double locks also make picking the locks more difficult.

See also