Watch case comprising: - a middle defining a peripheral track; - a rotating bezel; - a toothed crown; - at least one angular indexing member that resiliently engages with the toothed crown to define a plurality of stable angular positions of the bezel relative to the middle; - a structure for detachably fastening the bezel on the middle; said watch case being characterized in that: - the fastening structure comprises a circular element supporting radially projecting fins, each capable of engaging with a bayonet formed in the middle; - the watch case comprises a coupling system comprising a male part and a female part, one of which is integral with the bezel and the other one of which is integral with the fastening structure, with this coupling system arranged to be able to adopt two following configurations: • a decoupling configuration, in which the male part and the female part are decoupled, thus rotationally releasing the bezel relative to the circular element; • a coupling configuration, in which the male part and the female part are coupled, thus rotationally securing the bezel and the circular element and allowing their combined bidirectional rotation between a closed angular position of the circular element, in which each of its fins is engaged in a corresponding bayonet, and an open angular position, in which each fin is disengaged from the corresponding bayonet so as to release the bezel and the circular element from the middle; - the bezel is mounted on the fastening structure with the possibility of axial clearance, when the bezel is mounted on the middle with the circular element in its closed angular position, between: • a deployed position, in which the coupling system is placed in a decoupling position and the bezel is capable of rotating in order to be placed in any one of the positions of the plurality of stable angular positions; • a retracted position, in which the coupling system is placed in a coupling position. - a middle defining a peripheral track; - a rotating bezel; - a toothed crown; - at least one angular indexing member that resiliently engages with the toothed crown to define a plurality of stable angular positions of the bezel relative to the middle; - a structure for detachably fastening the bezel on the middle; - the fastening structure comprises a circular element supporting radially projecting fins, each capable of engaging with a bayonet formed in the middle; - the watch case comprises a coupling system comprising a male part and a female part, one of which is integral with the bezel and the other one of which is integral with the fastening structure, with this coupling system arranged to be able to adopt two following configurations: • a decoupling configuration, in which the male part and the female part are decoupled, thus rotationally releasing the bezel relative to the circular element; • a coupling configuration, in which the male part and the female part are coupled, thus rotationally securing the bezel and the circular element and allowing their combined bidirectional rotation between a closed angular position of the circular element, in which each of its fins is engaged in a corresponding bayonet, and an open angular position, in which each fin is disengaged from the corresponding bayonet so as to release the bezel and the circular element from the middle; • a decoupling configuration, in which the male part and the female part are decoupled, thus rotationally releasing the bezel relative to the circular element; • a coupling configuration, in which the male part and the female part are coupled, thus rotationally securing the bezel and the circular element and allowing their combined bidirectional rotation between a closed angular position of the circular element, in which each of its fins is engaged in a corresponding bayonet, and an open angular position, in which each fin is disengaged from the corresponding bayonet so as to release the bezel and the circular element from the middle; - the bezel is mounted on the fastening structure with the possibility of axial clearance, when the bezel is mounted on the middle with the circular element in its closed angular position, between: • a deployed position, in which the coupling system is placed in a decoupling position and the bezel is capable of rotating in order to be placed in any one of the positions of the plurality of stable angular positions; • a retracted position, in which the coupling system is placed in a coupling position. • a deployed position, in which the coupling system is placed in a decoupling position and the bezel is capable of rotating in order to be placed in any one of the positions of the plurality of stable angular positions; • a retracted position, in which the coupling system is placed in a coupling position.