From the Manufacturer… The Original McKenzie® Lumbar Roll has helped hundreds of thousands achieve freedom from common low back pain. An adjustable elastic strap lets users secure the roll to standard chair backs and auto seats. The strap also lets patients attach and wear the roll around the waist. The strap is easily removed when not in use. Use at a desk, in the car, and at home to ensure proper posture througout the day. Standard density.