Assembly for protecting a product against theft, includes a first part having a spike intended to pass through the product, and a second part provided in a first zone with an orifice for inserting the spike and locking elements to prevent the spike from being withdrawn after insertion. The second part includes at least one second zone for inserting the spike in a plurality of possible positions, the two parts are assembled with one another and kept in two possible modes of assembly. In a first protection mode, the spike is inserted into the orifice of the second part and the locking elements are activated so that a user cannot separate them without a tool; in a second temporary-assembly mode, the spike is inserted into the second zone and held therein in a temporary-assembly position such that a user can separate the two parts from one another without a tool.