Abstract: The present invention provides a return port cover that can close and open a return port separate from tubing movement caused by stretching or contracting under stress or other induced pipe movement from downhole conditions. For example, the return port cover can assist in preventing pack “fluffing” by preventing unintended fluid communication through an associated downhole tool regardless of the position of a circulating valve means. The return port cover can be biased, so that in one position it closes the port and in another position opens the port based on relative tubing placement at different portions of the fracturing operation or other well treatment operations.