(PS150) Preferred by some winemakers over Sodium Bisulfite. It is a granulated powder that releases sulfur dioxide when dissolved in a liquid. Added in small doses directly to fresh juices 24 hour before adding yeast. This is done to kill wild molds and bacteria that naturally come with these fruits which can cause off-flavors in the finished wine. Also, used in stronger doses with water as an equipment sanitizer. Use on fermenting vessels, hydrometers, wine bottles, hoses, air-locks or any other glass, plastic, metal or wood that comes into contact with your wine. A 1/16 teaspoon to one gallon of water or juice imparts 55 p.p.m. of sulfur dioxide. Comes with complete directions.