Good used on stubborn stains such as concrete remains, obfuscations on acid-resistant surfaces and also to solve / break up toilet blockages. While it is recommended by the manufacturer, the acid always be diluted but is is very dirty, a direct discharge possible, but be careful: Wear direct discharge ALWAYS respiratory and eye protection. The vapors combine with the moisture in the mucous membranes to light acidity. This is highly corrosive.
