Features: New bio balls with larger bacterium cultivation area. 15 * 16mm size, 100pcs bio balls included. Increase dissolved oxygen levels and improve biological filtration. Great for aquarium, fish tanks, koi ponds, waste water systems, etc. Specifications: Color: Blue Material: PVC Quantity: 100pcs Size: 15 * 16mm / 0.59 * 0.63in Weight: 1g(1pc) Package Size: Approx. 17 * 12 * 3cm Package Weight: 114g Package List: 100 * Bio Balls