Titrets Sulphur Test Kit, 10 per Box
You can use this kit to test the sulfite, or SO2, level in your white wine. If you do not have enough your wine may not have as long of a shelf life as you would like. If there is too much, you may actually taste it in your wine.
This is a great tool for any serious winemaker.
Each titrets sulphur test kit is good for ten tests.