Abstract: An assembly comprising a bracelet (1) in special spring steel, adjustable by individual shaping on every wrist, and comprising a circular hole (3) in its flat central part (21). The bracelet is covered with an removable and replaceable elongated sheath consisting of a single piece of elastic fabric. A case is interlocked in the hole (3), the fabric of the sheath being interposed between the case and the bracelet, without damage to the fabric. A tension ring situated in a lateral groove (17) provided on the periphery of the case cooperates with the lower surface of the flat part (12) of the bracelet for the removable fixing of the case on the bracelet.