Z-Tech Series 6AZAMP Z Tech Series 6A Head and Neck Restraint The Series 6A has new features never seen before in the Head and Neck Restraint market. These new Patent Pending features include a high back providing more natural pull angle and easier side to side movement; and our Advanced Axis Adjustment system allowing you to adjust shoulder width, arm angle, and arm width (to fit different body shapes and sizes and works for different race seat configurations.).