The ProtoShield makes it easy for you to design your own circuits. You can easily solder through-hole (TH) or surface-mount (SMD) ICs onto the prototyping area to test them with your Arduino board. The SMD area is designed for a maximum of 24-pin SOIC integrated circuits, while the TH area provides plenty of space for the necessary components around your project. You can even attach a mini breadboard (not included) to the prototyping area for a solder-free operation. The prototyping area also includes two power lines (IOREF and GND), two LED pads, and SPI signal breakout pads for boards that only have SPI on the ICSP header, such as the Zero. Main features: - 1.0 Arduino pin layout - 1 ICSP connector footprint - 2 LEDs and resistor area - IOREF and GND power lines - SPI signal pads - 24-pin SMD footprint (50 mils pitch).