The HiTechnic Servo Motor Controller for TETRIX™ connects to an NXT Intelligent Brick sensor port and will enable you to control up to six R/C-type servo motors for use with TETRIX robots, enabling you to add proportional positioning to your robotic creations. A total of four DC Motor Controllers and/or Servo Controllers for TETRIX can be daisy-chained to provide additional motor and/or servo outputs on each port.