There are at least two different ways you can configure this circuit board. Version A has components soldered in the appropriate locations so that it will work as an Arduino shield. Version B is configured to be a “daughter card” it also has a socket for an Arduino shield. This way you can mount at least three Arduino shields on to one Arduino. You can also reconfigure the pins to avoid conflicts between the different shields. Oh yeah you can also pop a little solderless bread board in the center. There seems to be plenty of room it and it does not seem interfere with any shields that I have attached.
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