STM32F103C8T6 ARM STM32 Minimum System Development Board, commonly referred to as the "Blue Pill" board. Includes two development boards with male pin headers (not soldered) and one ST-Link V2 compatible USB device for programming/debugging.

Powerful ARM Cortex MCU Microcontroller chip clocked at 72MHz Can be flashed with an Arduino-compatible bootloader.

For details, search for "stm32duino blue pill", also see "stm32duino" and mentions on Hackaday

Includes ST-Link V2 programmer (random color and markings - most are gray, blue, brown/gold, or green)