#AdafruitInAustralia. The FeatherWing Doubler is essentially two FeatherWing Proto boards in one. The benefit of the doubler is to be able to use a Feather board and another compatible board simultaneously side-by-side when stacked on top of Doubler proto board. It includes 1 set each of Feather stacking headers and Feather female headers.
Buy FeatherWing Double from Pakronics:
http://www.pakronics.com.au/products/featherwing-doubler-prototyping-add-on-for-all-feather-boards-ada2890