Loose fit: These bottoms are loose and relaxed for enhanced comfort. Thanks to DryVent™ fabric that's both windproof and waterproof, the Build Up Trousers are just what's needed on epic backcountry adventures. But while they deliver long-lasting protection in the harshest winter conditions, they're breathable enough to stop you from getting hot and sweaty as you tear it down the slopes. There are articulated knees that reduce friction and enhance mobility, and the lower legs are elasticated for a better fit.