BioGuard SilkGuard Complete Multi-Benefit 3 Inch Chlorinating Tablets are a revolutionary product exclusive to BioGuard. These chlorine tablets differ from traditional chlorine because the SilkGuard Technology actually softens the water by attaching to hard water components and metal surfaces, which protects your pool surface and equipment from scale, corrosion and staining, all while killing bacteria. SunShield Technology offers protection from the sunlight while the SmartGuard Technology helps the tablets last longer than traditional chlorine tablets. Last but not least Algae killing crystals help stop algae before it starts.