aquarium  filter cotton 100% Polyster material.)Suitable for filtering in aquarium with all kinds of water quality, product is resizable. Larger surface good for denitrifying bacterial to grow, which is good for fish clean up once erery month, effectively improves water quality and dramatically reduces fish death rate. It can be washed and reused, environmental friendly, SGS qualified. Lenth X Widh X Thick 39 X 05 X 1 Inches