It's been 91 years since Rene Lacoste first made his signature polo shirt, a short-sleeve number with a soft ribbed collar he could fold up to block the sun. And nearly a century later, the classic shirt is still an essential piece of any man's warm weather wardrobe. They're the T-shirt's more sturdy, well-dressed cousin. And having a few well-fitting polos—in classic neutrals as well as those colors that always seem to get you compliments—is an effortless way to look at once casually cool and put together. Whether you're wearing it with a pair of shorts and sandals or under a summer-weight suit, there are four styles you should seriously consider owning. Herewith, a few of our favorites.