These Duofold Men's Mid Weight long underwear bottoms are PERFECT. They are a soft flannel jersey material that's thinner yet warmer than conventional "thermal" wear with it's waffle (supposedly warm air trapping) material. The lack of bulk allows them to be worn underneath jeans or sweats or what have you. They are ultra comfortable, too. They're also easily machine washed & dried. By contrast, the thermals have a reinforced crotch which tends to rip away from the thinner adjacent material. So, if these hold up, I will buy another half dozen for next winter and never go back to thermals again. Great product.