EXCELLENT MECHANICAL FILTRATION: The use of filters socks IMPROVES WATER QUALITY by trapping debris, detritus, excess food, sand, coral and moreHIGH QUALITY PROFESSIONAL GRADE: These filter socks are designed to be sturdy, strong, and heavy duty to be RE-USABLE and cleanedCRYSTAL CLEAR WATER: These 200 Micrometre felt filter socks trap smaller organic matter and debris that larger or mesh filter socks do not catch to provide crystal clear waterREDUCES NOISE AND SPLASH in your aquarium/pond overflow sump systemcolour: whiteMaterial: polypropylene PPsize: diameter 105mm; overall length 380mmPackage Contents: 4*aquarium filterOnly the above package content, other products are not included.Note: Light 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.