The protective helmet shall meet the following specifications:
(1) DESIGN. One which is specifically designed for motorcycle riders and motorcycle passenger use.
(2) EXTERIOR SHELL. A hard exterior shell of nonshatterable material, resistant to impact and penetration.
(3) CRADLE. A firmly secured shock absorbent cradle for the head designed to support the helmet and maintain separation between the head and outer shell. Materials used in this portion of protective helmet shall be of durable quality and with characteristics that will not undergo appreciable alteration under the influence of aging or of the circumstances of use to which the helmet is normally subjected. Materials commonly known to cause skin irritation or disease shall not be used for these parts of the assembly which come in contact with the skin.
(4) PADDING. Impact-resistant, absorbent padding or cushioning material of substantial thickness in all areas where the head is in close proximity with or may contact the outer shell.
(5) CHIN STRAP. A permanently attached adjustable chin strap that will hold the helmet securely in place. A rider must at all times, while a motorized vehicle is in motion, have a chin strap firmly in place on or under the chin.
(6) VISOR. Not required, but, if the helmet is so equipped, the visor must be flexible or of a snap on type; however, no external projections shall be more than one-quarter inch above surface of the exterior shell.