Whats the deal with dermarollers?

[Plan C]

I've been researching into dermarollers and there seems to be differing opinions on them. I'm looking for a way to improve absorption of minoxidil because I can't always apply it twice a day and it seems like a dermaroller could assist me with this.
What is the correct size to get? I have short-medium length hair.
How often should you use it?

 

[LBerg12]

I have been asking the same thing. It looks painful as hell, but it seems to actually work. I don't know how I feel about making my scalp bleed and then putting minoxidil on it, but if it works for you than by all means... Let me know if you end up using it - good luck bro