Titrets provide a fast and easy way to Test the sulfite (So2) levels in your wine. Each titret will accurately read sulfite levels between 10 and 100 ppm (parts per million). contains 10 vials, enough for 10 tests. Comes with complete directions. Requires the titrettor hand tool. Monitoring and controlling the sulfite levels in your wine during bulk aging and during bottling is a big advantage. By keeping your wine at the optimal So2 level during these times, your wine will retain its Flavor and color to the highest degree possible. Each of the 10 vials has titrating solution stored under a vacuum. Just load the titret vial into the titrettor hand tool, to draw or suck controlled amounts of wine into the vial until a color change is noticed. Determine your reading by matching the total volume collected into the vial with the graduated marks on its side.