the nikon optester and takagi mt3, both of japan, are all of original design. the topcon vt s of japan is of original design, but topcon has also made knock-offs of the greens' refractor and the ao ultramatic. rodenstock in germany has developed many of their own models, as well as copied the ultramatic with their phorovist 200. the marco rt-300 of japan is an original design which borrows heavily from the ultramatic. in the 1930s, stearman in the uk and ellis optical co., also in the uk, both made an improved version of the genothalmic refractor called the british refracting unit, and stearman also made a knockoff of the greens refractor. china makes numerous unbranded knockoffs of the ultramatic.