The CT-UNO combines the simplicity of the UNO’s Optiboot bootloader (which load program faster), the stability of the FTDI and the R3 shield compatibility of the latest Arduino UNO R3.
Besides, we know many are using Android phone which comes with USB micro-B cable (power bank also require micro-B to charge), therefore, to lower down the cost needed for customer to get started, we populate the USB micro-B socket for USB connection! Program can be loaded from Arduino UNO by utilizing your Android phone USB cable. Select “Arduino UNO
For more detail: Introducing CT-UNO, Cytron version of Arduino UNO