Contents: 500g x 2 (mesh wrap). Compatible with: Freshwater, saltwater and grass nitrate culture. You buy bag of premium quality 1kg (2 x 500g) ceramic filter rings. Our filter rings are ideal for aquarium and pond filters. < p>These filter rings are packed in mesh bags - they are easily cleaned in the filter. In addition, they can be removed from the bag and placed in the filter. Large surface area allowing beneficial bacteria to colonize and water to be biologically filtered by the removal of ammonium and nitrites. Note: You will receive two 500g mesh bags, which means there will be 500g per bag.