These Level 1 pants (drawers) were designed by the US military to help soldiers survive through any weather condition they encounter. As the first level in the 7 level layering system, they are worn against the skin. Because of the special durable construction of the fabric it not only provides insulation, it aides in the transfer of moisture (known as moisture wicking), all without the bulk.
What this means for you is that during that cold camping night, your light weight thermal pants will keep you insulated and comfortable. And what about hiking? The fabric in these drawers is highly breathable and fast drying. This cooling system, again without the bulk for easy movement, is moisture wicking and will, therefore, keep you cool during the warmer parts of the day and warm during the colder weather.
These drawers are very durable and do not restrict movement. So go ahead and take that camping trip with confidence, just make sure to take along your ECWCS Level 1 silk weight thermal pants.