Every man needs a selection of undershirts in his wardrobe. Regardless of outfit, an undershirt creates a smooth look and prevents sweat from soaking into your clothing. The enduring classic undershirt is the crew neck. That fitted, banded neckline works under almost everything you wear and often does double duty as outerwear. Crew necks are invisible under buttoned shirts and ties as well as under turtlenecks, some polo shirts and many sweaters. If you keep a few buttons of your shirt undone or wear vee-neck tops or other shirts with a lower neckline, a crew undershirt will show. That's not necessarily a bad thing, as some men like the top of their tee peaking out.
Crew neck tees also follow fashion a bit. You can move away from the standard white, loose-fitting tee to shirts in navy, gray, black and even trendy fashion colors. If you prefer a closer fit, some crew neck undershirts are made of stretch cotton and cotton blended with spandex, for a flattering body-hugging fit that won't ruin the lines of close-cut shirts.