Electronic nicotine delivery systems are commonly known as e-cigarettes but are also known as vape pens, e-cigs, tanks, e-pipes, e-hookahs, mods, vapes, and more. Some are designed to resemble traditional cigarettes, cigars, or pipes. Tank systems, for example, are larger devices that don't seem like other tobacco products. Some of them look like pens, USB sticks, and other commonplace things.