I saw this very long Dizi in one of the booths in the Shanghai fair.
I'm not sure how long, but it is much taller than an average Chinese man.
You'll need 3 persons to play the flute: 1 to blow the flute, the other 2 to do the fingerings.
The flute has 2 mokong (the hole where you put the dimo) because the vibrations from 1 is not enough.
The flute is in the key of C.
Below is a slightly shorter low D dizi, placed alongside a low G and a low Bb. The low D dizi has 2 mokong as well but can be handled by 1 person alone.