A system isolates a control system for a downhole tool from the internal pressures in the tubing in which the tool is mounted. The index so generated is useful in two-pass information retrieval systems. The design allows a load such as a large electrical or telephone box to be transported and unloaded by a single operator. Each snoop filter device includes a plurality of parallel operating port snoop filters in correspondence with the plurality of dedicated input ports that are adapted to concurrently filter snoop requests received from respective dedicated memory writing sources and forward a subset of those requests to its associated processing unit. The process according to the invention is characterized in that at least the stabilizing edge comprises a synthetic fiber material, preferably a cellulose-based fiber material, particularly paperboard material.