FOR USE IN 24" AQUARIUMS. FILTER PLATE DIMENSIONS ARE 584MM BY 292MM (23" BY 11 1/2"). CARBON CARTRIDGE INCLUDED IN BOX. IT CAN BE USED IN EITHER A FRESHWATER (TROPICAL) OR MARINE AQUARIUM. MADE BY INTERPET. I HAVE TWO OF THESE, SO £4 EACH OR £7 FOR THE TWO. COLLECTION FROM WOODINGDEAN, BRIGHTON OR CAN DELIVER LOCALLY FOR COST OF.