Folding buckle is a device that can be adapted to any type of flexible bracelet, even those originally designed for a pin buckle. It allows to index a size and to keep it in memory.

Towards the end of the 20th century, folding buckles sometimes replaced pin buckles. They made their way in particular to watches with closed backs and a little less to watches with open backs because they can in some way impede the view of the movement.

Advantages: It allows the length of the strap to be indexed only once, thus reducing wear and tear on the strap at the fastening point.

Disadvantages: When the watch has a transparent back, a folding clasp can limit the visibility of the movement.