Fine fiber. Collects the smallest dirt particles in the water – filter wool (fine) has been developed for universal use. Very suitable for crystal clear water. Rinse in lukewarm water prior to use to guarantee optimum filtration, replace the filter wool every 4-8 weeks. The filter wool (fine) is made from 100% polyester, it is environmentally friendly and seawater proof. Ideal to be used in combination with Flamingo filter wool (medium-fine). Always put coarse filter wool before fine filter wool in the filter to avoid rapid blockage of the fine filter wool by coarse dirt.