When it comes to attaching telescopes to mounts, two standards have been established: the relatively narrow rails introduced by the Japanese manufacturer Vixen and the wider Losmandy rails. The latter are 3 inches wide and are mainly used for heavy telescopes.
Most telescope manufacturers follow these standards. Losmandy in particular also offers accessories that follow the Vixen standard.
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William Optics
Vixen Style Mounting Base
$ 41.90
ready for shipping in 3-5
weeks
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William Optics
Tragegriff 243mm
$ 104.00
ready for shipping in 3-5
weeks
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ABM
Bracket for Astrobox
$ 36.90
ready for shipping in 24
h