【Effective in cleaning】 - Effectively help you clean the tank, water pipe and other parts of the toilet. 【LONG-LASTING】 - Each toilet cleaner tablet lasts up to 5-7 Days (or 20 flushes daily), 12 tablets are for 2-4 months supply. BTW, each toilet tablet's lifetime may vary. 【HOW TO USE】 - DO NOT tear off the blue outer protective film, which is soluble in water tank directly. Please leave the toilet tank cleaner in the water tank for at least 10 minutes to dissolve sufficiently until water gets blue before flushing. 【points for attention】 - When the blue toilet bowl tablet dissolves completely, the blue will fade, a new toilet tank cleaner should be put into the tank. This product cannot completely replace the toilet brush. It is mainly to help maintain a clean toilet tank and reduce the dirt accumulation on the tank. Please clean the toilet tank with a toilet brush before the first-time use, so as to make a better use of this product. 【WARM SERVICE】- Vacplus service team is always standing behind all the products. If you have any problems or questions, please feel free to contact us.