After 15 hours of research, plus testing Thinx, Dear Kate, and PantyProp during our own cycles, we wouldn’t replace pads, tampons, or a menstrual cup with period underwear. Although a pair can in fact absorb up to two tampons’ worth of liquid (the exact amount depends on the model), our testers found the underwear too cumbersome to change out of (and carry around) when not at home. It’s also prohibitively expensive, unless you’re willing to constantly wash and dry pairs—at one point, I used over $100 worth of underwear in just 24 hours. But it can work as backup leak protection or as an option for very-light-flow days. If that’s appealing, Dear Kate and Thinx both work well, depending on your style and color preferences.