The cross-grain mahogany back center patch is necessary for the stability of the back along the center seam. These patches are made from pieces mahogany that have been glued up cross-grain for stability to form a single patch approximately 18″ to cover the back strip and joint on the back.
The mahogany back braces come as a set of three. The high quality genuine has been resawn to about 9mm in width and about 19mm high. There is one for each of the back braces for the guitar described in the book and dvd. The braces are slightly over sized and must be trimmed and shaped before gluing.
There are few colors that go with both spruce and cedar tops as far as bindings go. And if you can find something that works it might not bend easily. I have selected jotoba for the bindings and backstrips for all my wood kits because the color goes with either spruce or cedar and it bends well.