Inro were small, rectangular lacquered wood or metal cases in which Japanese gentlemen carried their necessities, attached to the obi (sash) by a silken rope. Usually they had four compartments, but when a clock movement was put into one, the case was unsegmented. Inro clocks are small and might be classed as watches, but the design of the movement is similar to that of small Japanese clocks. The clock was usually the simple verge variety with a balance wheel and a revolving chapter ring. It was a self-contained unit that slipped in and out of the inro case, which usually had a compartment in the lid for the key.