UNIVERSAL BIO MEDIA BAG - Aquarium mesh filter media bag is for small filter media, like pelletized carbon, granular carbon, zeolite, peat, crushed coral, Ammonia remover and ceramic rings, etc. Especially optimal for activated carbon. CUSTOMIZE YOUR AQUARIUM - Mesh filter media bags are for your freshwater, saltwater, or reef tank, small or large. You can choose the filter media best for your fish tank according to your expertise, optimize your filter meet the needs of your aquarium or pond and the fish and livestock you have. HIGH QUALITY - The aquarium filter media bag is made of nylon and the zipper is made of plastic which would not rust and produce harmful substances. The nylon mesh bags ' tear open, safe, , washable and reusable. CULTIVATE ECO WATER ENVIRONMENT - Place High Flow zipper mesh bags filled with of media in flowing water. Help to create quality living environment for your fish pet. Purified water quality, rapid probiotics cultivation, restore the high-quality water source in nature Your fish pet farming need a good water source and manage. size:15x20cm colour:White , Black Package Contents: 48 x white aquarium filter bag 48 x black aquarium filter bag 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.