 It is the LiPo Charging BFF. Best friend forever. Add on for the QT Pi. Take your BFF and you take a QT Pi and you just set them back to back like that. Now you can see this example here I've got some header pins on there. This gives you a JST plug for adding a LiPo or lithium ion battery. It has a little on-off switch there that you can use to turn on and off the battery power to the board. This makes for really great wearable projects. The QT Pi M0 plugged right into the BFF and I've soldered those with the cast-alated pads. Got this nice little Neopixel demo running here. Battery power. You can turn that on and off with the power switch and we can also charge that right off of the USB. My best friend and yours forever. It is the LiPo Charging BFF. Add on for QT Pi.