I was confused by the mix of reviews saying "these are super thick!" and "these are transparent!" Turns out they're both--they're a sturdy canvas that isn't likely to rip any time soon (and as white pants they're far more likely to stain before they rip)... but they're *also* a bit transparent like you sometimes might see in a white shirt that isn't particularly thin, just transparent. So go with underwear that matches your flesh tone and you'll be fine. The cut is cute and the stretch makes them comfortable.

BTW, since their sizing guide didn't help me At All, their "size 29" is roughly a size 4-6 in US sizes.