It is a facsimile of the black D-35 Custom that Cash played for ca. 20 years, and was the guitar most often associated with him.
Obviously, this one is also all black, but beneath that black gloss finish lies an Englemann spruce top with forward-shifted, scalloped, 1/4-inch bracing, giving this guitar tremendous sound.
With its all-black, Geib style hardshell case, it lists at $5599.
This is a Special Edition guitar, signed by C.F. Martin IV and by John Carter Cash.