General Application: Alleviates pain in the lower back. Medical Application: Effective relief from Sacroiliac Joint Syndrome, a condition that causes pain in the lower region of the lower back. How It Works: The Sacroiliac (S.I.) Back Belt provides stabilization to the hips and sacrum, reducing strain to the lower back. Design Theory: The SI Back Belt is wrapped lower, around the hips, than most back supports. The compression pad combines with a second set of exterior straps to apply effective compression on the sacrum. A non slip gel helps keep the SI Belt in place. It is also contoured to offer an extremely comfortable fit. Size Chart: (based on pants size) Women: Item 5200 Small 2 – 4 Item 5201 Medium 6 – 10 Item 5202 Large 12 – 16 Men: Item 5200 Small 22 – 30 Item 5201 Medium 32 – 38 Item 5202 Large 40 – 48