These pants are kickin! Flexible room, yet slim fitting leg so you don't feel like a scrubby balloon. I'm comfortably a US size 4, but often wear size 2. I originally ordered the pants in a S, but had to exchange them for an XS (they run a bit big in the waist...the sizing guide is definately off). Overall, super comfy, warm, and withstand water saturation well. Overall, great buy.