Hayward Perflex EC40 Tank Lid (ECX10334P) brettaqualine The 679 4 is a practical The 679 4 is a practical service part when a compatible Harmsco BF1200 filter needs an aligning rod to restore dependable internal alignment This heavy duty 8 ft probe is intended for pool and spa chemical feeder systems where dependable readings are important for water balance This Hayward Perflex EC40 tank lid is a replacement component for compatible EC40 DE filter systems where the existing lid is cracked A correct replacement lid can extend the service life of the filter and help avoid larger equipment changes when the filter body and internals are still in good condition