This manual dual spring swivel and tilting mechanism is ideally purchased when desiring to continue to use an old style 4 legged chair base. The mechanism also works especially well with large heavy chair backs. It is only available in 17 1/2" hole to hole length. There are two main differences between this mechanism (#224754) and the #475.
However, both bells fit up to large executive size swivel office chairs and maybe used interchangeably equally well.