To keep prices low.  Bench tools are controlled via an Arduino Uno via I2C protocol. The Arduino uses a blank PCB board propagated with an RJ11 jack,  XHP-JST, and other electrical components.   The RJ11 jack is connected to the IC2 Pins located at A4 and A5.  XHP-JST connectors are used to make connections with external sensors or inputs.  Lastly, the PCB can accommodate other electrical components: LEDs, Resistors, ICs and the like.