Listing is for ( 1 ) : DEEP BLUE PROFESSIONAL "CUT TO FIT" CARBON FILTER PAD ( 1 ) 18" x 10" CARBON PAD AVANTAGES 18 x 10 inch pad - Cut to fit media pad traps micro and macro organic particles, foreign debris, and excess fish food. For use in custom sumps/refugiums, hang-on filters, prefilter boxes, and more. Safe for both freshwater and marine aquaria ! Promotes a healthy aquatic environment ! New thicker, more rigid design for extended use ! 18" x 10" CARBON PAD: Chemical & Mechanical Dual stage filtration Absorbs odors, discoloration, and toxins 1/2" Thick Safely suspends and removes micro & macro organic particles, foreign debris, excess fish food and aquatic waste. Promotes beneficial bacteria colonization for a healthy aquatic environment. For freshwater & marine aquariums. Use Cut-To-Fit for: Filter cartridge frames Hanging filter Trickle filter Wet/dry filter drip tray Powerhead attachment Canister filter Pond filter