The Ergodyne N-Ferno Thermal Liners #6852 are high-quality 2-layer hat liners designed for industrial and construction workers. The liners feature a cotton shell for added comfort and breathability, making them suitable for long hours of wear. The N-Ferno brand by Ergodyne is known for its durable and effective protective gear, making these thermal liners a reliable choice for keeping workers warm and protected in cold weather conditions.