When both hands held in sarpashirsha hasta is crossed at the wrists, we get the Naagabandha hand gesture.
lets take a look at the viniyoga shloka: (uses)
Etasya viniyogastu naagabandhe he samataha
This gesture is used to show how the snakes twine or their nature of coiling and encircling. Check out the video for Naagabandha hastas from .37 s to end.