PUMABoys' Core Logo Mesh Pant

what is the material like? mesh/silky or cotton/sweatpant?

size charts?

I have an 11 year old boy and hes a pretty big boy he wears 18-20 husky usually and hes thicker in the waist mostly. Will the Xl fit him comfortably?

Do these have a pull string to adjust the waist size?