Review on visionreast Men's Ultra Soft Thermal Underwear Set | Warm Base Layers | Long Johns Set for Skiing Winter by Zachary Pete

I bought based on waist size. I'm 33 so I took the L which fits my waist up to 34. They fit fairly well, snug which I would prefer for something I wear under other clothes. I got them mainly for skiing to wear under pants and jackets. The L shirt also fits well, but it would be nice if you could choose different pant and shirt sizes if needed. I could see how some people approach one thing but not another. It's been a fairly warm fall so far, so haven't had a chance to test them in cold weather, but they're too warm to wear at home, so that's a good sign of cold weather.