These are uniform shorts used for both devlopmental and elite athletes.   the girls shorts fo to the mid thigh while the boys shorts go a couple of inches above the knee. It is advised to order one size larger than your child's shorts size. 
 
The sizes are Youth Extra Small (YXS), Youth Small (YS), Youth Medium (YM), Youth Extra Large (YXL), Adult Small (AS), Adult Medium (AM), Adult Large (AL)