Abstract: Deployant or folding clasp including, hinged around a support, a first arm being hinged to a first stirrup member, and a second arm to a second stirrup member. This first stirrup member forms part of a first single-piece cap whose bottom surface defines, with one end of this first arm, in any angular position thereof, a space for the passage of a wristband strand having a thickness smaller than or equal to a given thickness, and this second stirrup member forms the bottom part of a second removable cap and includes at least one securing means arranged to cooperate, by clamping around an orifice of a wristband strand, with a complementary securing means of a removable top part of this second cap, to adjust the useful length of this wristband strand.