“These are so, so soft,” one reviewer, who called the bra liners the ″best summer purchase,″ says. “I tuck them under my breasts and then ease my bra on top and they stay in place all day. At the end of the day they might be very damp, but my skin is comfy. Also, I’m able to rotate through them, letting them dry in between, and get a good three uses out of each before I wash them. Even then, they don’t smell.” Others say they’re great at relieving discomfort. “Even if I sweat profusely (working outdoors in Florida in the springtime), they absorb everything,” a customer wrote. “I used to have constant irritation under my breasts due to sweat. I have eczema and it would flare up all the time in the summer. Now I’ve worn these for a week straight and 95 percent of the irritation is gone.” To buy: $15 for three; amazon.com Shoppers recommend finding your ideal size by measuring across your chest or simply dividing your band size in half. Then, select the bra liner size that best corresponds to this measurement. For the best fit, you’ll want to make sure that the liner isn’t too long, but can lie comfortably across your chest. When they’re tucked so only a little bit (about a quarter-inch) shows below the underwire, they fit securely with little risk of falling down. Summertime sweat may be an inevitability, but it doesn’t have to make you uncomfortable or ruin your outfit. A simple bra liner might just become your new secret weapon.