A One Hitter is designed exactly for one toke and is filled with a small amount of tobacco which you can smoke directly. One Hitters can be made of glass or metal. One well recognized type it the Dugout Pipe, a convenient aluminum Pipe for precise dosages.
The classic one-hitter often imitates the appearance of a cigarette and after smoking discreetly disappears in a pack of cigarettes or, as in the case of the DugOut pipe, in a specially designed case. Other one hitters as the PotHit are not designed for discretion, but for accurately controlling the amount you want to smoke.