The SCX Digital Control Unit allows expansion from 3 to 6 drivers, and includes the #20090 Control Units Connecting Cable. In addition to the #25000 Control Unit - you will need a #20060 Electronic Hand Throttle for each additional driver, and you will need to have at least two #20070 Electronic Transformers (one is included in each SCX Digital race set) when racing with more than 3 drivers. Made by SCX, compatible with all other SCX Digital products and guaranteed for a period of 2 years from the date of purchase. | 
