Board has 8 positions for driving servos between two positions and 8 inputs for fascia controllers (sold separately) or toggle switches. Octopus III uses the remote board (sold separately) to align the servos and has automated endpoint adjustment as well as full manual control. Ideal for use with miniature servos and the servo mounting kit (sold separately). Power with 7.5-24V filtered DC (do not use AC and please do not use old "powerpacks" - they are not filtered). Octopus III has a built-in switching power supply for high efficiency and greater range. You should budget 1 Amp per board with 1 Amp overhead (for when the servos are driving to new positions). So 3 Octos should have a 4 Amp power supply. Board is 2.5" x 1.9" in size.