The copper anode rod electrolyzes anion and copper ions and releases them into the water, which can break the outer wall of harmful substances and algae spores quickly and efficiently, thus achieving the effect of sterilization and inhibition of algae. It's chemical-free, efficient and eco-friendly, no irritation, a natural way to maintain water quality for a long time. Note: Size and color may be slightly different because of manual measurement and different light conditions. Thanks for understanding. Specifications: Material: Copper Alloy Screw Thread: 6mm Item Size: 120 * 18mm / 4.72 * 0.71in Item Weight: 230g / 8.11oz Package Weight: 12.5 * 12.5 * 3.5cm / 4.92 * 4.92 * 1.38in Package Size: 263g / 9.26oz Packing List: 1 * Copper Anode Rod