LTWHOME Pre-Filter Sponge Roll Fit for South Ocean Five AOF10112 Aquarium Filter, 2.75 by 5.9-Inch (Pack of 12) They are just Activated Carbon

They are just Activated Carbon impregnated foam

VACUUM CLEANER WASHABLE FILTER

Simply cut holes in the desired position with scissors to fit most filter boxes

Compatible with Eheim Classic 2213 / 250 filtration systems

There is no poly side to these filters

LTWHOME Pre-Filter Sponge Roll Fit for South Ocean Five AOF10112 Aquarium Filter, 2.75 by 5.9-Inch (Pack of 12) They are just Activated CarbonPacking include: 12pcs filter sponge. Size: 15 x 7cm 5. 9" x 2. 75"(H*D), 3. 5cm 1. 37"(Inner Hole Dia) . Provides efficient water flow with less clogging for long lasting filtration. Enhances biological filtration. Change every 3 4 weeks.