Material: The filter balls are made of 100% recyclable polyethylene, weight: 500g, 1 pack (0.5kg) can replace about 18 kg of filter sand. Upgrade : A revolutionary new generation of filtration material, provides faster filtration speed and collection capacity. Dense design: High water permeability, lighter, more efficient, excellent filtration , eco-friendly and recyclable. washable, lump-free, very durable. Applicability: Filter ball is a spherical filter material made of fibers widely used in various water treatment industries. Wide Range of Applications: Filter balls suitable for all sand filtration systems, for swimming pools, filter pumps, aquariums, etc. It can also replace filter sand. which can effectively filter fine suspended matter and improve water quality.