Styles

There are two distinct subtypes of contemporary metal handcuffs: one in which the cuffs are held together by a short chain, and another, of more recent origin, which uses a hinge for this purpose. Since the hinged handcuffs are somewhat smaller when fully extended they are seen as being more easily utilized by a police officer who has relatively small hands, and are also regarded by some observers as more secure because the wrists end up being held closer together than with the chain subtype, and are also bound more rigidly. A third type, the rigid handcuff, has a metal block or bar between the cuffs. While bulkier to carry it permits several variations in cuffing, and example of rigid handcuffs are Hiatts Speedcuffs as used by most police forces in the United Kingdom. Both rigid and hinged cuffs can be used one-handed to apply pain-compliance/control techniques that are not workable with the chain type of cuff. Various accessories are available to improve the security or increase the rigidity of handcuffs, including boxes that fit over the chain or hinge and can themselves be locked with a padlock.

Handcuffs may be manufactured from various metals, including carbon steel, stainless steel and aluminium, or from synthetic polymers.

Sometimes two pairs of handcuffs are needed to restrain a person with an exceptionally large waistline because the hands cannot be brought close enough together; in this case, one cuff on one pair of handcuffs is handcuffed to one of the cuffs on the other pair, and then the remaining open handcuff on each pair is applied to the person's wrists. Oversized handcuffs are available from a number of manufacturers, as are juvenile-sized restraints, though none of the latter in current production are approved for use by the United States National Institute of Justice.

Double locks

Handcuffs with double locks have a lock-spring which when engaged stops the cuff from ratcheting tighter to prevent the wearer from tightening them. Tightening could be intentional or by struggling, when tightened the handcuffs may cause nerve damage or loss of circulation. Also some wearers could tighten the cuffs to attempt an escape by having the officer loosen the cuffs and while the cuffs are loose attempt the escape. Double locks also make picking the locks more difficult.

There exist three kinds of double locks as described in a Smith&Wesson brochure:

Lever lock

These are double-locked by fully lifting the lever with a fingertip and then allowing it to return. This causes the lock spring to move into a position that locks the bolt thus preventing the cuff from being further tightened. Thus NO tool is required to double lock of this kind.