Medical vest for High Frequency Chest Wall Oscillation (HFCWO) system, comprising at least a device comprising a deformable chamber and at least a port in communication with the chamber configured to let a pressurized fluid flowing alternatively in and out the chamber so that the inflatable device alternatively passes from an inflated configuration to a deflated configuration, characterized in that the device is configured to essentially expand along one single direction when passing from the deflated configuration to the inflated configuration.
