The flask’s glaze has radium ore, which radiates alpha rays. The rays create negative ions, so that when you put water in the flask, the water molecules make small continual movements like a babbling brook. This makes the water taste smooth and delicious.
Tap water has acidity. But, if you put it in the Negative Ion Drop Flask, in about 7 hours, it will become almost neutral. The taste will be as smooth and delicious as store-bought bottled water.
When you put sake in the flask, the alpha rays circulate in the flask to make the sake age quickly in a week. You can enjoy smooth-tasting sake without having to wait for ages.
The flask is good for whiskey, shochu (distilled spirits), sake, wine, black vinegar, soy sauce, etc.
The radium ore in the glaze is a source of radon hot springs. Those hot springs are well known for their antioxidant quality. Due to that quality, the flask can maintain these effects semi-permanently.