Mechanical filtration: the use of filter socks improves water quality by trapping debris, detritus, excess food, sand, corals, and moreHigh-quality professional quality: these filter socks are designed to be strdy, strongWater: these 200 micrometer felt socks capture smaller matter and debris that larger or mesh filter socks do not catch into the waterReduces noise and splash in the aquarium/pond overflow systemMultiple Use-These unique filter mesh bags are easy to fill and empty with a top with zippered design to ensure the filter cartridge is safe. The bags are durable, washable and can be reused. Color: WhiteMaterial: Non-woven + Plastic Size: 105x380mmPackage Content: 12 x Aquarium Filter BagOnly the above package content, other products are not included. Note: The light and different displays may cause the color of the item in the picture to be slightly different from the real thing. The allowed measurement error is +/- 1-3cm.