This product is a 40% solution of Sodium metabisulfite and distilled water. This liquid is a yellowish solution with a pungent sulphur odour. It is commonly used for removal of free chlorine and as a biostatic and in food and pharmaceutical preservative, waste water dechlorinating agent, lab reagent. As sanitization and cleaning agent, It is used as a cleaning agent for potable water reverse osmosis membranes in desalination systems. It is also used to remove chloramine from drinking water after treatment.