"EDUSTAK PRO demonstrates the fuel stack technology that is powering cutting-edge transport solutions and generators. Assemble your own fuel cell stack of individually connected cells and then power up with the refillable HYDROSTIK PRO metal hydride cartridges. EDUSTAK comes in 5-cell and 10-cell stacks depending on your hydrogen power requirements. Plus, no tools are necessary to assemble the cell stacks. Requires Hydrofill PRO (PN FCH-020 SET) to refill the already included Hydrostik Pro"