The closed design provides a significant level of added safety in the classroom by reducing the potential for spilling chemicals. It is possible to use a chemical solution for several days, as they are contained inside the structure, allowing use over multiple class periods. The tanks can easily be filled, and emptied when needed. Because the apparatus has a small footprint, only a minimal amount of chemicals will be required to perform an electrolysis experiment. With this Electrolysis Apparatus, almost any type of electrolysis experiment can be done because of the high-quality, built-in, platinum coated titanium electrodes, which are resistant to corrosion. The N-00006 Genecon V3, hand-held DC generator, can be used as a power source for this product. The collection tubes are graduated to allow you to measure and to compare the ratio of the two gases that were created. Contains the following: Electrode: a pair of platinum coated titanium electrode Soft silicon plugs (white): 2 pieces Soft silicon plug (blue): 1 piece Cap: 1 piece