Underdays underwear sizing runs the gamut from XS to XXL and has been designed specifically to be the reprise that women need from their current underwear. In the pair’s research, they scoured through countless competitor reviews, conducted surveys of their target audience and had over 50 rounds of user-testing before they signed off on their designs.

“The design process really started and ended with insights from our customers, which we think has never really been done before in the lingerie industry,” Mackenzie says. “One of the most interesting things we found out from all of our research, is that most women find that their gusset (the internal lining inside of a brief or thong) is not long enough and doesn’t give the protection they need.”

Why this female-founded lingerie brand is about to become your latest obsession