Choose superior comfort and durability with the lightweight and ventilated Danmar Hard Shell Helmet! Made of shock-absorbent foam lining and a hard plastic ventilated shell. Vinyl-coated foam is easy to clean – only soap and water are required! An easily adjusted chin strap with snap closure is included. The Danmar Hard Shell Helmet is very lightweight at an average weight of 17 ounces (weight varies slightly by size). When determining which type of headgear to select, consider: the degree of physical activity, potential striking surfaces (floor, walls, furniture, etc.), nature of self abusiveness, severity & frequency of seizures or spasticity, length of time worn, etc. Note: While we believe that headgear can substantially reduce the risk of head injury we emphasize that there is no known device for preventing all injuries. Only you the customer are in a position to evaluate the particularized needs of the individual client in each environment. It is essential that professional and medical expertise be utilized in rendering decisions regarding headgear use. When utilizing the size chart (included in product photos) to determine the size, the measurements are as follows: (A) Circumference Range, (B) Occipital, (C) Ear To Ear. Please see the size chart for more details. Please note: Proper fit is important for the comfort of the person wearing headgear. Measurements should be determined by professional personnel.