The Leg Spacer has a strap adjustment which helps secure the Leg Spacer for a custom fit. In pressure-diffusing memory foam covered in a moisture-resistant (hospital grade) Steri-Plus cover to give high levels of comfort when relieving low back strain by properly aligning knees and hips. Therapeutically designed to help relieve pressure and strain on the lower back, hips and knees while you sleep by helping keep your legs aligned with your spine.