(From the wife) My physical therapist recommended this product when treating me for symphasis pubis dysfunction during my first pregnancy last year. I didn't purchase it then since I only had a few weeks to go in my pregnancy. Finding myself pregnant again this year, I bought one during my first trimester and wore it regularly/daily. I found that I didn't need the underlying belly-strap, and just used the non-elastic band. Either way, it provides better support if you Velcro the ends to itself (rather than to the belly-strap that is elastic). It was comfortable to wear directly against the skin as long as the Velcro was completely covered. I typically wore it over my pants - which had the side benefit of helping to keep my maternity pants from sliding down. =]This product is very helpful in holding your hips in place, especially when the hormones of pregnancy cause your ligaments to loosen and everything feels like it's slipping. I felt much more secure walking with the belt on. For belly support, I also purchased a Prenatal Cradle (Best Cradle (Medium)- with adjustable straps), which has also been critical to my mobility during this pregnancy.I purchased the L/XL. My hips average 40-43 inches.