There are three main types of handcuffs: chain, hinged, and solid bar. While they are harder to carry, rigid handcuffs allow a number of differences in cuffing. Both rigid and hinged cuffs can be used one-handed to apply pain-compliance/control techniques. Different accessories are available to improve the security or increase the hardness of handcuffs. These include boxes that fit over the chain or hinge and can be locked with a padlock.