You can attach up to 16 P2B8 controllers to one DROID master module. Each has eight push buttons and two potentiometers (knobs). In your DROID patch you can assign arbitrary functions to the bottons and pots.
Shipping includes a short ribbon cable for connecting the controller to the master or the the previous controller. If you want to place the controller further away from the master you can purchaser longer ribbon cables here in the shop.
The color of the LEDs in the buttons is white.