Gap's cotton thongs have been my go-to undies for the last 15+ years. This time I decided to try a few new styles. Since I wear size large in the cotton thongs I ordered the breathe thongs, lace thongs, and no-show thongs in size large, too. The cotton thongs fit as expected. The breathe, lace and n...o-shows were all too big. I exchanged the larges for mediums. The mediums fit perfect in the breathe and lace styles. The mediums in this (no-show) style are a little snug. I guess I'm truly in between sizes for this style. The larges fit, but they're almost loose. I'm not sure if there's enough tension in the fabric for them to stay put under clothes. The mediums aren't uncomfortable, but they're definitely stretched to the max. I'm not sure if I'll end up keeping either size. For reference, I'm 5'2", 145 lbs. Small-ish waist, big butt, thick hips and thighs.