The invention comprises a case having an opening, electronic parts and a wiring board installed in the case, a connector plug body fixed to the case, and a lid disposed in the opening of the case. The ligand portion of the composition has affinity for and forms a complex with the selected ions, thereby removing them from the source solution. This metadata can subsequently be used by a block-level controller to more efficiently read the sequential data stream back to the file system using read-ahead processes. The seam spacer is made of a material which is pliable and which has water passages for draining water. The second database records correlations of the items between the two data sets.