<Li> The 165 m (541 ft) Singapore Flyer has cylindrical externally mounted motorised capsules and is described as an observation wheel by its operators, but was also credited as "world's largest Ferris wheel" by the media when it opened in 2008 . </Li> <Ul> <Li> The 135 m (443 ft) London Eye, typically described as a "giant Ferris wheel" by the media, has ovoidal externally mounted motorised capsules and is the "world's tallest cantilevered observation wheel" according to its operators, who claim "The London Eye is often mistakenly called a Ferris wheel . This is not the case: first, the passenger capsules are completely enclosed and are climate controlled; secondly, the capsules are positioned on the outside of the wheel structure and are fully motorised; and third, the entire structure is supported by an A-frame on one side only ." However the Singapore Flyer subsequently billed itself as the "world's largest observation wheel", despite being supported on both sides, and the official londoneye.com website also refers to the London Eye as "Europe's tallest Ferris wheel". </Li> </Ul> <Li> The 135 m (443 ft) London Eye, typically described as a "giant Ferris wheel" by the media, has ovoidal externally mounted motorised capsules and is the "world's tallest cantilevered observation wheel" according to its operators, who claim "The London Eye is often mistakenly called a Ferris wheel . This is not the case: first, the passenger capsules are completely enclosed and are climate controlled; secondly, the capsules are positioned on the outside of the wheel structure and are fully motorised; and third, the entire structure is supported by an A-frame on one side only ." However the Singapore Flyer subsequently billed itself as the "world's largest observation wheel", despite being supported on both sides, and the official londoneye.com website also refers to the London Eye as "Europe's tallest Ferris wheel". </Li> <Ul> <Li> The 120 m (394 ft) Melbourne Star (previously the Southern Star) in Australia has ovoidal externally mounted motorised capsules and is described by its operators as "the only observation wheel in the southern hemisphere", but also as a Ferris wheel by the media . </Li> </Ul>

What is the world's tallest cantilevered observation wheel