The Doctor's handcuffs

Two sets of handcuffs were owned by the Doctor during their thirteenth incarnation. She carried them in the pockets of her coat.

When she and Yasmin Khan were captured by the Lupari Karvanista, the Doctor tricked him into imprisoning her and Yaz using these handcuffs. What she did not tell the Lupar was that the handcuffs were voice activated, meaning the Doctor could free herself and her companion whenever she wanted.

After Karvanista left the two of them handcuffed and footlocked to a gravity bar on an acidic planet about to be consumed by a giant red star, the Doctor and Yaz quickly escaped to the TARDIS. However, the cuffs took a while to respond to the voice command, due to the Doctor believing to have been programming them with a Scottish accent.

After a long escapade across the doomed world, the Doctor and Yaz reached the TARDIS, where the Doctor finally managed to activate the voice command, albeit by sheer accident. (TV: The Halloween Apocalypse)