I carefully deciphered through all of these different micro needling devices. I chose one (a different brand) that I thought would be good, when I received it it was not at all. I decided to go with Dr pen. There are many here that sell Dr. Pen brand. And after investigating with Dr. Pen itself, there are many unauthorized sellers on Amazon. That's why the bad reviews. I chose this one because it seemed to be an authentic retailer of the brand. It saved me money than going direct with the company, and it was risk free with my prime membership, also with discounted prices on extra cartridges to add on right away, which I took advantage of because I had a good feeling this was a legit retailer. I just received it today, it really works! It's quality product and I'm glad I took advantage of the extra savings ordering cartridges with the purchase! Now, time will tell if it helps with my areas of concern. However, all of the videos I have watched, I do not recommend sliding it over your skin! But to place it over an area for a second lift up and place into the next area, etc... The needles move way too fast and it causes scraping, cutting over the skin, which I have found on my tomato skin testing. Not ideal. The nano head breaks up the dead skin cells on the surface and exposes trapped sebum, etc... That can then be gently exfoliated out, ideally with an enzyme exfoliant and ultrasonic current. TG