Deveoloped by the IAOM, the SI-LOC is tapered and wider at the innominates, so pressure is distributed more evenly. Unlike other belts, the internationally patented SI-LOC is not bulky under garments and breathable fabric adds comfort. Wide, medical grade, non-slip pads ensure that the SI-LOC stays in place. Available in two sizes. To fit, measure the pelvic circumference at a level one inch above most superior aspect of the greater trochanters.To fit, measure the pelvic circumference at a level one inch above most superior aspect of the greater trochanters. Measure carefully. Non-returnable. This small/medium size fits up to 30" - 46".