Restraining bolts were compact, cylindrical devices designed to be attached to a droid for the purpose of restricting its functionality and ensuring its obedience. Once attached, a restraining bolt prevented the droid from performing any actions not authorized by its master, and it also compelled the droid to respond to signals emitted by a portable control device known as a caller. These commands typically consisted of just three basic instructions: "Come," "Halt," and "Orders." Some droids experienced intense fear at the very thought of restraining bolts. Furthermore, restraining bolts played a role in the construction of Jawa ion blasters; they were integrated into the blaster's firing mechanism alongside accu-accelerators sourced from a starship's ion engine.
Droids were generally unable to detach restraining bolts themselves. However, in one exceptional instance, the droid L3-37 liberated numerous other droids from their restraining bolts during a revolt involving slaves and droids on Kessel. Sabine Wren occasionally threatened Chopper with a restraining bolt when he exhibited disobedient behavior. The astromech droid known as "Chopper" utilized his spark projector to release AP-5 from the confines of his restraining bolt. The BX-series droid commando ND-5 was equipped with a restraining bolt that subjected him to the will of the criminal Jaylen Vrax, but it also enhanced his capabilities beyond standard battle droid specifications. ND-5 managed to offer some resistance by verbally protesting the orders enforced by the bolt, but he was still obligated to carry them out. When his companion Kay Vess succeeded in freeing him from the restraining bolt, ND-5 did not lose his individual consciousness as he had feared.