Spresense is a compact development board based on Sony’s power-efficient multicore microcontroller CXD5602. It allows developers to create IoT applications in a very short time and is supported by the Arduino IDE as well as the more advanced NuttX based SDK. The Spresense Extension Board has the following connectors in addition to Arduino Uno compatible pin sockets:

• 3.5 mm headphone jack
• MicroSD card (not included, but we carry 'em in the store)
• Extra USB port
• Multiple microphone pins

The Spresense main board and extension board are connected by a Board-to-Board (B-2-B) connector.

Note: This is just the extension board. You'll need the main board as well.