I have the XL session harness, my waist is a 38 and it fits me just fine. If you have a belly above the waist, the spreader bar straps will accomodate upto I figure a 42” circumference. Solid unit all told, I am a heavy dude(250lb), and tend to tear apart harnesses (mostly stitching) due to stress load (big kites & heavy wind) and looking at this harness, I figure that the stress points are well stitched and actually relocated to minimize the “stretching” of the stitching, which in my mind is what causes all the problems. So with great anticipation do I look forward to putting this harness through all its paces. On another note, being larger I have never used waist harnesses, always seat harnesses, with the leg straps designed the way they are, I see that my mobility is going to be increased substancially, allowing me to do grabs and board offs all that much more easier.