The Old Fashioned glass, lowball glass, or rocks glass is a short tumbler used for serving an alcoholic beverage, such as whisky, with ice cubes (“on the rocks”). It is also normally used to serve certain cocktails, such as the Old Fashioned, from which it receives its name. These glasses are also commonly referred to as DOF glasses. DOF is an abbreviation of Double Old Fashioned.
Old Fashioned glasses typically have a wide brim and a thick base (or tunc), so that the non-liquid ingredients of a cocktail can be mashed using a muddler before the main liquid ingredients are added.
Old Fashioned glasses usually contain 6–10 US fl oz (180–300 ml). A double Old Fashioned glass (sometimes referred to by retailers as a DOF glass) contains 12–16 US fl oz (350–470 ml).