Made with a special two-layer soft jersey knit, Pepper Bi-Ply's long underwear is sure to keep you warm when you need it most. The unique double layer construction traps warm air between the two layers for excellent thermal retention. These women's thermal long johns are knit with Mtf soft spun polyester fibers that transport moisture away from the skin to keep you warm, dry and comfortable.Bi-Ply midweight bottoms are a tried-and-true favorite choice for comfort while protecting against the cold. Modern technology working to keep you warm – the long underwear features Mtf soft spun polyester fibers that keep moisture away from your skin, while the double layer construction helps to trap warm air and ensure excellent thermal retention.