EasyPro FFM Filter Floss Bio-Media for Ponds, 3000-Foot Roll Ribbon type material commonly used in our aquafalls pond filters Flat strapping that is embossed on both sides creating additional surface area for bacteria Lightweight, will last indefinitely and has no effect on water quality (unlike lava rock) Upgrade to this Bio-Media as each media bag will weigh 4-lbs instead of 40-lbs when filled with lava rock