A bracelet or strap for a watch case including a first arm inside which is housed a first printed circuit portion and a second arm, where the first arm is extended by a median part arranged to be situated underneath the watch case and which includes a second printed circuit portion connected to the first printed circuit portion by electrical connection, where the first printed circuit portion carries at least one electrical energy source and a microcontroller for powering and controlling a pressure sensor, where the median part is covered by an insert arranged to act as a seat for the watch case, where a housing, inside which the pressure sensor is arranged, is provided in the insert and communicates with the exterior to allow the pressure sensor to be placed in contact with a surrounding medium, and the pressure sensor is mounted on the second printed circuit portion with the insertion of a sealing gasket between the housing and the second printed circuit portion.