These are GENUINE U.S. MILITARY M-65 Insulated Pants Liners. They are ultra lightweight, nylon, quilt lined and insulated. These liners are made to button into the cold weather M-65 field trousers but can be worn and modified to fit into your favorite pair of pants by sewing buttons into your pants. These make a world of difference when trying to stay warm.

Some button open on the sides and some do not - depending on the size and time period they were produced.