Cannon Breath cleanses and strengthens the parasympathetic nerves, and adjusts the digestion. Cannon Breath is Breath of Fire done through the mouth.
Pucker the mouth to form an O shape. (Relaxed puckered shape)
As you breathe in and out, the pressure should be in the cheeks, although there is no bulging of cheeks.
This breath is often done at the end of an exercise.