An apparatus comprises a gauze layer comprising a gauze material, a first area, a gauze first side and a gauze second side. The devices provide an improved accuracy of the time and amplitude characteristics of the compression impulses and functioning in modes of generation both the ante-grade wave and external counter-pulsation. The directory object ID can be a unique identifier of a record maintained by the directory service system. The output of a P-diff first stage may be connected to the input of an N-diff second stage and the output of an N-diff first stage may be connected to the input of a P-diff second stage thereby creating a \u201ccross\u201d coupled structure. The configuration of the first notch and the second notch is correspondingly disposed along a vertical projection plane with respect to the substrate.