The SparkFun Large Digit Driver can easily be attached to the back of the 7-segment display by soldering all 10 castellations pins at the bottom of the board as well as the two additional castellations at the top. Keep in mind that the Large Digit Driver requires both 12V for the LEDs and 5V for the on-board TPIC6C596 IC. Each driver is equipped with six input pins and six output pins, these make the driver capable of being chained together. The input/output pins are listed as GND (Ground), LAT (Latch), CLK (Clock), SER (Serial), 5V (Power for the driver IC), and 12V (Power for the 7-segment display). We actually used the SparkFun Large Digit Driver in our AVC Battle-Bot Arena to display times and scores!