Binoculars, field glasses or binocular telescopes are a pair of identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction, allowing the viewer to use both eyes with binocular vision when viewing distant objects. Most are sized to be held using both hands, although there are much larger types. Small, low-power binoculars for use at performance events are known as opera glasses (see below). Many different abbreviations are used for binoculars, including glasses and bins.