Mad Dog Concepts3-Pack Boys Pajama Pants - Soft Micro Fleece PJ Bottoms for Kids, Printed Plaid Design - Boy's Sleepwear

So the size charts are numerical, but these are size M. What size is a Medium in the numerical chart?

What size is large?

Are the waists made for husky kids? It's practically impossible to find tall slim boys pajamas that aren't skintight in areas for a preteen.

What size is xl