A pair of shackles
Shackles are items that spawn with the Guard, Archer, and Knight classes. They are used to capture or restrain people. The arms and legs must be shackled separately. It takes a few seconds to successfully and they must be next to you at the end for you to finish. Shackles can be unlocked with the shackle key spawned by the above classes.
See also: Rope shackles