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. Also compatible with Skullerz 8945F(x) Universal Bu