This battery adapter connector allows you to plug two batteries with T-Plug style connectors together in Series to power a single speed controller. This adapter is built with the newest AMASS brand T-Plugs to be able to handle the higher currents of larger aircraft. To use this adapter, both batteries must have the same mah capacity. For example, two 3-cell 2200mah batteries can be connected together to form a 6-cell 2200mah battery. You can also use cells with different number of cells, as long as the capacity is the same. You could take a 2-cell 2200mah battery and connect it with a 3-cell 2200mah battery to make a single 5-cell 2200mah battery.