The N-Ferno 6811Z Zippered Rib Knit Beanie Hat provides warmth, as well as the option for 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 (sold separately) for work in cramped spaces. Made with 100% soft dry acrylic and 40-gram 3M flex stretch insulation for a warm, comfortable fit. Ideal for construction, baggage handling, mechanics, freight, mining, oil and gas, warehousing, refrigeration and more. Also great for outdoor sports like skiing, snowboarding, trekking, mountain climbing and hunting.