Green vs Blue Pro Micro
They are not completely compatible with the old blue colored ones. Some sellers even list both, giving you a "color" choice, but they are two different designs. Details in this post.You do not want these green ones if you are building a Let's Split style keyboard that uses two Pro Micro's. This includes the Foobar, and the other split keyboards I have made.
The original Sparkfun Pro Micro is Red. Color may not be a reliable way of identifying these. You should compare the physical differences in the components near the USB connector.
