Function: Swimming pool filter sponge is used to clean impurities, leaves and pollutants in the swimming pool, so that the swimming pool can be clean. High quality: High quality sponge makes it have excellent ductility and can have stronger filtering capacity. However, the swimming pool contains some pollutants, so you need to take them out for cleaning regularly to reduce the possibility of the filter sponge being corroded and decomposing, so as to extend its service life. Cost saving: The swimming pool needs regular maintenance, and the filter elements needs to be replaced frequently to maintain cleanliness. The pool filter sponge can be cleaned so that it can be reused, which helps you save a lot of costs. Easy to use: You just need to take it out regularly (about a week), clean it and put it back in place Suitable for: Compatible with foam and jet pure spa swimming pool, bathroom, fish tank. A SECURATY FOR YOUR FISH HABITATE: give your fish pet a securaty habitate! these cylinder pre-filter sponge suit for all shrimp tank owners and anyone else who has small fish in their tank,provide them a safe environment. HIGH QUALITY MATERIAL: these sponges are made from the high quality filtration foam,safe to your fish, good for freshwater and saltwater environments. Color: Black Material:sponge Aperture: 20mm Package Contents: 40x filter sponge Only the above package content, other products are not included. Note: Light reflection 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.