EXCELLENT MECHANICAL FILTRATION: The use of filters socks IMPROVES WATER QUALITY by trapping debris, detritus, excess food, sand, coral and more HIGH QUALITY PROFESSIONAL GRADE: These filter socks are designed to be sturdy, strong, and heavy duty to be RE-USABLE and cleaned CRYSTAL 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 water REDUCES NOISE AND SPLASH in your aquarium/pond overflow sump system colour: white Material: polypropylene PP size: diameter 105mm; overall length 380mm Package Contents: 4*aquarium filter 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.