A submersible pump is inserted into this filter bag to prevent sediment from clogging it. Use of the filter bag will prolong the life and reduce cleaning/maintenance of the pump. A must have for EVERY pump! Small Filter Bag works with the following pumps: Eco 66, Eco 100 and Eco 132. Large Filter Bag works with the following pumps: Eco 185, Eco 264, Eco 396, Eco 633, Mag Drive 250 & 350, Little Giant PE-1, LG 1, NK-1 and NK-2.