This Oase Replacement Proficlear Filter Fleece 750 spare 3 micron Filter Fleece is simple to replace on the new ProfiClear Fleece 750 pond filter module. The Oase ProfiClear Premium Fleece 750 provides brilliant viewing depth in koi ponds up to 38,000l in size and extracts even the tiniest organic waste products from the pond water via the disposable filter fleece cleaning system filtering out particles as small as 3 micron (0.003mm).