Bioguard Skim Mor uses a mycelx coated material. This Mycelx material attracts and traps oil, cosmetics, lotions, pollen and pieces of fine debris that your filter may miss. These impurities can dull your pool water, cause a waterline build-up and even clog your cartridge or DE filter. This product stretches to fit virtually all skimmer baskets. It is proven to extend the life of the filter and reduce maintenance time. Easy to use, just slip onto your skimmer basket!