The N-Ferno 6811ZI Zippered Rib Knit Beanie Hat with Bump Cap Insert provides warmth, as well as lightweight protection from bumps, scrapes, bruises and other minor head injuries. Wear this soft cuffed beanie alone or open the back zippered compartment to add the Skullerz 8945 Universal Bump Cap Insert (included) for work in cramped spaces. Made with 100% soft dry acrylic and 40-gram 3M flex stretch insulation for a warm, comfortable fit. The impact-resistant shell is made of lightweight durable polypropylene and is designed with maximum ventilation for breathable airflow that doesn't compromise protection. An interior foam pad reduces impact but does not absorb odors for fresh all-day wear. Bump caps are typically worn in spaces where worker-generated impact head protection is needed, like low ceilings, beams, low pipes and other bump hazards.