Duo is a thumb-size development board made to simplify the building process of Internet of Things (IoT) products. Everything you need is built into the Duo. It contains WiFi, BLE and Cloud, all in a compact form factor that makes it ideal for your first prototype, a finished product, and everything in between.<br><br> With the help of RB Link, a RedBear expansion board, you can attach add-on modules without any soldering at all. You can get your prototype up and running in no time. You can buy Grove Starter Kit for Photon to develop projects.<br><br> <b>Features</b><br> Both Wi-Fi and BLE capabilities<br> Free Particle io Cloud Services<br> Arduino, JavaScript and Python support (WiFi &amp; BLE only)<br> Broadcom WICED SDK (Wi-Fi &amp; Bluetooth Dual Mode)<br> Free Android and iOS Apps<br> Integration with RBLink and work with Grove system<br> <br> <b>Specification</b><br> STMicroelectronics STM32F205 ARM Cortex-M3 @120MHz, 128 KB SRAM and 1MB Flash<br> Broadcom BCM43438 Wi-Fi 802.11n (2.4GHz only) + Bluetooth 4.1 (Dual Mode) combo chip<br> On-board 16 Mbit (2 MB) SPI Flash<br> Integrated chip antenna with the option to connect external antenna<br> 18 I/O pins<br> RGB status LED<br> Small single-sided PCB for easy mounting on other PCB boards<br> Duo comes with headers soldered<br> 20.5mm x 39mm<br> <br> <b>Part List</b><br> 1 x RedBear DUO ? Wi-Fi + BLE IoT Board <br>