I purchase my dermarollers from www.owndoc.com and I use the 2.0 cm roller. I am still rolling and did it last weekend, in fact.
My younger brother who sees me about every three to four months mentioned how smooth my face looked the last times I saw him.
The subcision treatments were, by far , the procedures that reduced the significance of my scarring. Dermarolling and 25% at home TCA peels also helped to stimulate the production of collagen in my skin. I buy mine from www.skinobsession. Definitely do our homework first as this is a powerful peel and you must wear eye protection. I have done four or five if them and your skin really peels!
Hope this helps.