Most surgeons use very small cannulas for facial fat grafting.
Most surgeons have moved away from sharp needles for fat grafting as it is safer and less traumatic to use blunt tip cannulas. I prefer the small 0.9mm cannulas from Tulip. They work well, the fat is smoothly delivered in small micro-droplets and only an 18 gauge needle is needed to make the incision through the skin for access.
Hope this information helps.
Cannula size for fat transfer
Based on the technique of liposuction and size of the liposuction cannula, and size of fat cells. The injection cannula is chosen