Lightweight thermal liner is shoulder-length to keep head, ears, and neck covered, and fits comfortably under helmets or hard hats without feeling too bulkyFour hook & loop straps on the exterior of the liner securely attach to the interior of a hard hatFeatures pockets by the ears designed to hold regular-sized hand warmers (sold separately) to keep ears warm and comfortable in extreme temperaturesElastic strip in the forehead area keeps the liner snug against the face to trap body heat in and keep cold outDetachable face mask design allows you to let in air or remove for speaking when neededHook and loop closures on the mouthpiece have a secure and adjustable fit to prevent the mask from moving aroundHard-shell design of the mask prevents it from being sucked into the mouth to allow plenty of breathing spaceMachine washable