justin first approached mike doolin, an innovative luthier with an excellent reputation, to build a double-neck steel-string guitar. justin wanted a guitar with two identical dadgad-tuned necks to expand on his unique two-handed tapping style. the challenge was to design an instrument that could handle 340 pounds of string tension and yet still be acoustically responsive. the instrument features many of doolin's innovations, including a pinless bridge, and adjustable neck angles. doolin and king chose an instrument with a modified jumbo-style body, cocobolo (rosewood) back and sides, and a redwood top. the redwood is incredibly strong and stable, while at the same time being dynamic and possessing a rich acoustic tone. they also decided on using b-band acoustic pickups, which are known for their excellent fidelity. the result is an unprecedented instrument, completely unique, with a wonderful tone. this can be seen on the song "knock on wood" and "crown" (unofficial title).