Total cervical arch support with a large trachea opening. Two-piece design. Latex-free Plastizote foam. Adjustable bilateral Velcro fasteners. Anterior and posterior rigid plastic reinforcements. Provides greater limitations for flexion, extension, and rotation. Height and circumference need to be measured to determine size. Cross reference measurements in the table below.Size: refers to the height of the collar. This is taken from the bottom of the chin to the top of the sternum. Measurement: refers to the circumference of the neck.