Product Description N-Ferno Warming Products include winter liners and other head wear designed to keep workers warm and comfortable. We’ve got versions for cool, cold, and extreme conditions with hi-tech fabrics and superior features for reliable warmth from ear-to-ear. In fact, most liners have pockets next to the ears to hold warming packs. From the Manufacturer N-Ferno Warming Products include winter liners and other head wear designed to keep workers warm and comfortable. We’ve got versions for cool, cold, and extreme conditions with hi-tech fabrics and superior features for reliable warmth from ear-to-ear. In fact, most liners have pockets next to the ears to hold warming packs.