I don't remember tbh. It's difficult to find any consensus on depth duration and frequency for it.
It generated a lot of talk on the hair forums because it was real clinical research.
Dermarolling/needling usually falls into two different approaches. You can go shallow (like 0.5mm) and do it more frequently, or go deep (1.5+ mm) and less frequently.
It's pretty damaging to the scalp if you try to combine very deep + frequent.
From what I've seen, I would go with 0.8mm at most. Deeper needles don't seem to be more effective at growing hair.
