this washing machine tub cleaning tablets are carefully formulated with sodium bicarbonate and sodium dodecyl sulfate. Designed specifically for delving deep into the interior of washing machines to effectively remove stubborn dirt and washing residues. The usage method is extremely convenient: Just put the cleaning block into the washing machine. After adding water， run it for about 10 minutes and soak it in warm water for a better effect. When using the washing machine for the first time， turn off the power and let it soak for 2 hthiss. It is recommended to extend the soaking time. Gentle and non-corrosive， it is suitable for various machine systems， such as drums and impellers. And it can remove the dirt that causes odors， helping to restore a fresh and clean environment.