A method for tracking objects entering and exiting an environment comprises providing stereo vision cameras positioned proximate to the paths to enter the environment, such that the stereo vision fields associated with the cameras substantially cover the paths. The noise absorbing material may absorb noise from a signal path in the substrate to prevent the noise from reaching other signals or signal paths. When the stem is in the lower position, the handling clamp is capable of being locked closed. A screw passes through the through hole, such that a screw portion of the screw is screwed to the sealing portion, and on the other hand, a screw head is fastened to the step portion of the through hole of the shaft portion. Moreover, according to some embodiments a comparator circuit generates a power indication signal when a substantially scaled processor voltage signal exceeds a reference voltage signal.