Okay, I'll admit I sat staring at this for a few weeks before I tried it out. The thought of putting needles into your face is really unappealing, but these needles really are small. I used the nano size needles when I first used this and honestly could not tell if the machine was actually getting my skin. I switched to the 12 needle tip. There is a huge difference between the nano and the 12. I'm not quite sure what the nano would be used for. I've never had Profesional microneedling and didn't know what to expect at all... But using the Dr. Pen at home really wasn't anything like what I was anticipating needling to be like. I did not use any kind of numbing agent. You can feel the needles poke you, but it's not unbearable. After, your skin will feel red and tender. I think it actually felt worse after than while in the process of needling. The machine comes with 6 disposable needle cartridges. (2) nano, (2) 12 needles, and (2) 36 needles pen tips. They are pretty easy to figure out how to put in the pen. The machine comes with some instructions and a guideline for depth to use at various parts of the face. The depth is adjustable by twisting the bottom of the pen - it goes from 0-2.5 and is clearly labeled. The speed is adjustable by the pressing the ON button multiple times. Long-press to turn off. The instructions do not tell you how to actually use this. How hard to press, how long to stay on one place, etc. I suggest watching some how-to videos online if you've never used one of these. I got this to try and stimulate growth in a damaged area of my skin - its too early to tell, but I have hopes that if it can reduce wrinkles it can reduce my skin damage too. Overall, pretty user friendly and surprisingly painless. I'll definitely keep using this.