Complete wet/dry filter combos are exactly what your tank is looking for enhanced biological filtration and simple setup. Each complete biological filtration system includes an overflow box, bio balls, a drip tray & cover, egg crate, filter pad, return valve, clear vinyl tubing, a 1 in. bulkhead and 3 ft. of 1 in. flex hose. The simplest choice for advanced aquarium biological filtration with wet/dry filters.