It seems, now that she's aware of it, to be made from rod no thicker than the wire of a coat hanger, but much stronger, and of enormous rigidity. She knows that because she can feel it, now that someone has been turning a central key, also of metal, which is T-shaped, and engraved, very finely, on one side only, with the map of a city whose name she once knew, though it escapes her now in her wretchedness at the band's expansion. With each turn of the key, it widens, causing her excruciating pain.