- Fits hip circumference size 26" - 54". Our non-restricting design fits both men and women. Petite Size fits hip size 26" - 31". Regular Size fits hip size 30" - 44". Plus Size fits Hip size 45" -54". - SI joint belt helps stabilize the sacroiliac joint (or "SI joint") that is hypermobile or inflamed, and reduces pelvic, lower back and/or leg pain (symptom of sciatica) caused by SI joint dysfunction. We strongly recommend that you wear the SI joint belt day and night for at least two weeks. Do not over tighten the belt. - LIGHTWEIGHT AND DURABLE - The perforated neoprene used in the inner belt is lightweight, breathable and pilling resistant. The ribbon fish fabric used in the secondary straps is breathable, elastic and pilling resistant. - STAYS IN PLACE - The anti-slip silicone strips on the inner belt prevents the belt from sliding up and down. You can wear it while doing physical activities but vigorous exercise is discouraged during the recovery period.