An exterior sub-assembly for a timepiece or watch or piece of jewelry, including a first component and a second component, arranged for a bayonet mount between two rims and two wings comprised in the first component and the second component, and capable of occupying an assembled and indexed position of the first and second components, this sub-assembly including a third ring-shaped component inserted between the first and second components, fixed in rotation with respect to one of these components and including an elastically deformable area, opposing a variable resistance torque to any relative tangential torque between the first and second components, and including a catch cooperating with a relief portion of the component that is not connected to the third component, wherein one particular catch angularly indexes these first and second components.