The Old Fashioned glass or rocks glass is a short tumbler used for serving tan spirits, 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.
Old Fashioned glasses typically have a wide brim and a thick base, 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 180–300 ml (6–10 US fl oz). A double Old Fashioned glass (sometimes referred to by retailers as a DOF glass) contains 350–470 ml (12–16 US fl oz).