It shall be unlawful for any person under the age of twenty-one to operate or ride upon a two-wheeled motorized vehicle unless he wears a protective helmet of a type approved by the Department of Public Safety. Such a helmet must be equipped with either a neck or chin strap and be reflectorized on both sides thereof. The department is hereby authorized to adopt and amend regulations covering the types of helmets and the specifications therefor and to establish and maintain a list of approved helmets which meet the specifications as established hereunder.