What you have purchased is a 420g high quality multifilter material in a bag. Our filter ring is ideal for aquarium and pond filters.< /p> These filter rings are housed in a mesh bag, they are easy to clean in the filter. Plus, they can be removed from the bag and placed in the filter. The large surface area allows beneficial bacteria to multiply and biologically filters the water removing ammonium and nitrites. Quantity delivered: 1 sachet of 420g