Easy to Use: All you have to do is remove the filter when you impact the electrode rod, and the excessive chlorination will cause the foam to rupture quickly. Normal levels of chlorine and bromine disinfection are good and these foams have been tested at normal levels. Practical Design: This foam filter will outlast your paper cartridges and can be washed and re-used several times over. Perfect in Use: Changing your paper filter cartridge is part of your routine maintenance for your pool and regular replacement of the cartridge can prove costly. These washable and re-usable foam filters will reduce your costs. Initial cost of this cartridge is slightly more than a paper cartridge yet will outlast a cartridge by a long way. Practical in Use: The filter is suitable for filter type A, which will meet your needs. Advises changing a paper cartridge each week, whereas these foams can simply be washed and put back. You should see a foam filter last around 2 months. colour:blue Material:sponge size: 20cm x 10cm x 4cm/7.9 x 3.9 x 3.9 inch(H x D) Center Hole Drilled:approx.40mm Package Contents: 4 x Pool Sponge Filter Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.