The nRF52840-MDK is a versatile, easy-to-use IoT hardware platform for Bluetooth 5, Bluetooth mesh, Thread, IEEE 802.15.4, ANT and 2.4GHz proprietary applications using the nRF52840 SoC.
The development kit comes with a fully integrated debugger (also known as DAPLink) that provides USB drag-and-drop programming, USB Virtual COM port and CMSIS-DAP interface.
The kit contains a Microchip USB 2.0 Hi-Speed hub controller with two downstream ports: one for DAPLink interface and one for nRF52840 USB device controller. The kit also features ultra-low power 64-Mb QSPI FLASH memory, programmable user button, RGB LED, up to 24 GPIOs, antenna selection for custom applications.
See nRF52840-mdk website  for more information about the development board and nRF52840 website  for the official reference on the IC itself.