This is an adapter for the standard 10pin 0.05" pitch ARM Cortex JTAG connector to a 0.1" (100mil) pitch header connector.
The JTAG adapter board kit is a useful accessory for connecting your Black Magic Probe JTAG/SWD adapter to development board featuring a 0.1" pitch header, like the Raspberry Pi or STM32 Discovery boards. Its also useful when you want to use flying wires connections and break out your Black Magic Probe to your breadboard or a 0.1" pitch custom JTAG connector. The pinout of this adapter is compatible to the STM32 discovery board ST-Link connector. It includes one additional pin to provide the TDO signal that is missing from the original ST-Link connector, adding JTAG capability.
The JTAG/SWD 0.1" breakout board kit comes with the 0.05" pitch header and button pre soldered. It also comes with a loose 0.1" 7pin right angle header and socket that can be soldered onto the breakout board by the user.