An object holding apparatus including a chuck for holding an object, a holder configured to hold the chuck, a generator provided in the holder and configured to generate a field related to an attraction force, a member provided in the chuck and configured to be attracted by the generator in accordance with the field, and a support configured to support one of the generator and the member. EGM signals from both the true bipolar pair and the integrated bipolar pair are simultaneously sensed and compared to determine which pair produced more accurate sensing of cardiac events. Subsequently, the compound layer is removed. In a second embodiment, the session control and media control messages are supported with a single bearer with a QoS that suits both types of control messages. The third stage comprises a pMOSFET serially connected with a nMOSFET, where their gates are connected together and to the output port of the second stage, and comprises a feedback pMOSFET or resistor to provide negative feedback from the drains of the pMOSFET and nMOSFET to the output port of the second stage.