The M65 pant liner is an inexpensive and great way to keep warm while working, sitting in a tree stand or around a campfire. Originally designed as a button in liner to the M65 military field pant, these were intended to keep you warm down to 14 degrees Fahrenheit (minus 10 degrees Celsius). Made a very comfortable ripstop nylon with stitched in insulation you will feel like you're wearing a blanket. If you do not have a way to button them in you can be creative and the warmth will be worth it. They also work great to line waders.