MECHANICAL FILTRATION: The use of socks IMPROVES WATER by trapping debris, detritus, excess food, sand, coral and more HIGH PROFESSIONAL : These filter socks are designed to be strdy, strong WATER: These 200 Micrometre felt filter socks trap smaller matter and debris that larger or mesh filter socks do not catch to water REDUCES NOISE AND SPLASH in your aquarium/pond overflow system REUSABLE - These unique mesh filter bags are EASY TO FILL AND EMPTY with top zipper design to keep filter media . bags are durable, washable, and can be reused. Colour:White Material:Non-woven + plastic Size: 105 x 380mm Package Contents: 12 x aquarium filter bag Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.