We built the HyperDown Pant for the big-game hunter who takes winter weather in stride. Insulated with 800-fill power PrimaLoft(R) Gold down blend, they're our warmest puffer pants. length easy-access side zips make for quick and easy layering, even over boots. 27D ripstop face fabric is doubled up on the seat and knees for added toughness where you need it most.