The USL Medical Lumbar Rolls are recommended to support on-going back conditions and injuries. Designed for everyday use in office chairs as well as providing excellent support in vehicles. Features: Secure Lock Buckle Elastic Strap is easily adjustable Breathable fabric allows increased airflow Durable fabric on sides which increases the cushions resistance & durability Sizes: 13312 Lumbar Roll Slimline Round - Diameter 6.5cm x Length 33cm 13163 Lumbar Roll Round Heavy - Diameter 11cm x Length 33cm 13164 Lumbar Roll D Shaped Regular - Diameter 11.5cm x Length 30cm 13165 Lumbar Roll Regular - Diameter 10cm x Length 33.5cm Instructions: You should position the USL Sport lumbar roll in the small of your back just above the belt line.