Check the listing for details. 6-Pack Pre-Filter Sponge for Aquarium Fish Tank Filter Replacement Foam Cover. Condition: New. Listed at 7.99 USD. Key Feature:Lifesaver: Keeps baby fish, shrimp, and snails from getting sucked into hob filters, power heads or canister filters by simply putting a pc of this pre-filter sponge over the intake.Improve Filtration: Does a good job in catching flake fish foods, plants and any other large particles floating in the water keeping the tank cleaner and last longer between cleanings.Maintenance: Rinse the sponge roll periodically based on the bio load of your aquarium tank. The material holds up well to being rinsed and reused and allows great water flow.This pre-filter sponge also can be used to dampen the outflow and make the water more stable for your betta.This prefilter sponge provide both mechanical and bio filtrationFor a snug fit, check the size you need carefully before placing an order.Note: The hole doesn't go all the way through the sponge. Package includes: For 0.4”: 6 pcs of prefilter sponge, 1.4"D X 2.4"H; the inside hole diameter is 1cm/0.4”For 0.6”: 6 pcs of prefilter sponge, 1.6"D X 2.8"H; the inside hole diameter is 1.5cm/0.6”For 0.8”: 6 pcs of prefilter sponge, 1.8"D X 3.2"H; the inside hole diameter is 2cm/0.8”For 1”: 6 pcs of prefilter sponge, 2.2"D X 3.9"H; the inside hole diameter is 2.5cm/1”