TROUBLE-FREE BIOLOGICAL FILTER WITH FLAT-PLATE DESIGN. FILTER PLATE HAS MORE OPEN SPACE WHICH ALLOWS FOR BETTER WATER CIRCULATION. FILTER PLATES ARE MADE OF A SEMI-FLEXIBLE, BREAK-RESISTANT PLASTIC. THIS UNDER GRAVEL FILTER USES THE SAME UPLIFT ASSEMBLY AS LEE'S® ORIGINAL UNDER GRAVEL FILTERS. SINGLE-PLATE INCLUDES FISH-SAVER ELBOW, SLIM DISCARD-A-STONE, AND ORIGINAL CARBON CARTRIDGE.