A collins glass is a glass tumbler which typically will contain 300 to 410 millilitres (10 to 14 US fl oz). It is used to serve mixed drinks, especially Tom Collins or John Collins cocktails. It is cylindrical in shape and narrower and taller than a highball glass. An example size is 2 1⁄2 in (6 cm) diameter by 6.75 in (17 cm) in height.