This is the Medium sized version of the Headmaster Collar.Soft, well padded and easy to adjust, it is an effective cervical support available in six different sizes ranging from infant to large adult. This model will fit medium sized adults with a chin-to-jaw measurement of 11.5cm (4.5\"). It is designed to maintain the head in its proper position but its inherent flexibility will allow for neck movement, both extension and flexion. It fastens securely using an adjustable strap that leaves the front of the neck free. It can therefore be used in conjunction with a tracheal tube where required.