Abstract: A key for holding a dial foot, the key including a cylindrical head arranged at the end of a rod, the head and the rod being coaxial, the head including a flat and a collar extending over a portion of its periphery in an angular sector defined around the longitudinal axis of the rod, on either side of the flat. The collar includes a cross section with a frustoconical shape and, with respect to the periphery of the head, forms a minimum radial projection, substantially zero, at the ends of this angular sector and forms a maximum radial projection between these ends.

Abstract: A dial including an external parts plate (11) intended to be visible for a user, resting on a bearing surface (120) of a support plate (12) on which it is superimposed, the external parts plate (11) and the support plate (12) being fastened to one another at their periphery by the cooperation of peripheral fastening members that they both include, and at their centre by the cooperation of central fastening members that they both include.