Alongside the development of the M-65 parka, a detachable liner was also created as a cold weather solution. This liner was made of nylon and polyester insulation with quilting to prevent the insulation from shif ting. By using these synthetic fibers, the liner achieved lightweight construction while maintaining insulation properties, surpassing the previous wool pile liners. The sleeve cuffs were equipped with tabs for attachment, a feature inherited from the M-50 field jacket. Although the liner was not originally intended for standalone use, it could be worn independently by attaching buttons, and additional pockets were added to enhance functionality.