Medical vest for High Frequency Chest Wall Oscillation (HFCWO) system comprising at least a device (1) comprising a deformable chamber (8) and at least a port (5 6) in communication with the chamber (8) configured to let a pressurized fluid flowing alternatively in and out the chamber (8) so that the inflatable device (1) alternatively passes from an inflated configuration to a deflated configuration characterized in that the device (1) is configured to essentially expand along one single direction (200) when passing from the deflated configuration to the inflated configuration.
