Thanks ladies! I used human hair. I usually keep my braids in for a month but I will keep these in for about 2 months. Yes my arms were tired. I haven't braided my hair myself in about 13 years so yes my arms, back and everything was hurting. I took out the cornrows I had in for about a month and I had about 2 inches of new growth so I am anxious to see how much I get when I take these out.