Magnetic manacles are restraining devices similar to handcuffs. Instead of using a physical chain, bar or hinge, it uses magnetism to hold the two bands over the wrists together. Magnetic manacles can also be programmed to de-magnetize at a certain time, releasing the prisoner.
The Nausicaan bounty hunter Kajek carried a pair of magnetic manacles as part of his standard equipment. When Cervantes Quinn got the jump on him on the Gorn controlled planet of Seudath, Quinn bound Kajek with the manacles and programmed them to release in four hours. (VAN - Declassified novella: The Stars Look Down)