These are the basic waffle or "grid" type thermals and are not heavy weight or "super duty" by any means. If you are planning a trip across the arctic tundra then "buck up" and buy a more expensive type. If however you are like me and just need something a little extra during the winter months to wear under your work pants, then these are just fine indeed. Just don't throw them in the dryer and cook em down a dozen sizes especially if you're kinda tall as they wil shrink up to your elbows.