$27 for a two-pack, at RibbedTee
An undershirt is your first line of defense against sweat stains. It's also a last resort, allowing you to strip out of your top shirt when things get steamy without stepping outside cultural norms. The key is finding the right balance. The perfect undershirt will be thin and breathable to keep you cool, yet substantial enough not to lose its shape and long enough to stay tucked in. Mike Schwartz, the founder of Ribbed Tee, says that the Towncraft 50/50 poly cotton undershirts—a discontinued department store staple of the 1970s and '80s—might have been it. Using a vintage tee for inspiration, he recently introduced his Retro Fit V-neck. Made in the US from a soft, loose knit 50/50 jersey material, the featherweight shirt feels like it's been washed a hundred times already. The fit is trim, skimming the body without being clingy. It's got a generously cut collar which stays concealed under your button down and the length is just long enough to stay put when tucked, but not too long to sport untucked if you're wearing it under a cardigan or simply with some shorts.