Use in: Hydroponic systems, ponds, aquariums, fish tanks, and reservoir. Intake hole: 1.10 inch (approx.). Diameter: 4.13 inch (approx.). Coarseness 25 PPI. Length: 5.91 inch (approx.). Inner Length: 4.33 inch (approx.) -- Intake hole is not all the way through. Package Includes: 1 PIECE of Overflow Filter Box Intake Round Pre-Filter Foam Sponge 5.91" x 4.13" X-Large The applications of our bio sponge filter are the most versatile. These can be used on the most common air lift bio sponge filter, hang on back type filter, and may be fabricated into a filter you would like. *This is for 1 piece of XL round filter sponge.* These pre-filter sponges are designed for canister filters and Aquaclear 70 and 110 filters. Can also work for Aqueon and other larger hang on back filters as well.