The Maternity SI-LOC is tapered and wider at the in-nominates so pressure is distributed more evenly. SI-LOC is not bulky under clothing, and the breathable fabric adds comfort. Wide, medical grade non-slip pads ensure the SI-LOC stays in place.  It includes a special, detachable support pad. To size: measure the distance form ASIS-dorsally around the back-to the other ASIS.