Afterbangs will NOT flex for a 5 5, 90 pound kid. I was in the same boat last year, then gained almost 30 pounds and 5 inches over the summer and I can still barely flex afterbangs. Get anthems or some old invaders, invaders are super light, SOOO cheap, and you'll be able to flex them. you most likely won't destroy them too, since you're a skinny kid.