Apparatus or systems which employ luminescence-quenching to produce a signal indicative of oxygen concentration. The light emitting element components include a first light emitting element component and a second light emitting element component. The overall portion of Si and SIC is a maximum of 60% by volume. Inverters, compare these impact detecting signals, with a threshold value and detect an impact when the signals exceeds the threshold value. Termination for the connection may be specified using a port and payload selector dialog that enables information associated with the port to be displayed to improve the port selection process and enables available channels to be viewed in a graphical manner. The folding level can beneficially include other recessed features, such as a fastening means to hold the segments together in a folded configuration, and a locking means to hold the segments secure when the segments are rotated 180 degrees with respect to each other so that the tops of the segments form a smooth flat surface with a straight edge.