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.

ABM
Mounting for Astrobox
$ 39.90
ready for shipping in 24
h

William Optics
Carrying handle 243mm
$ 112.00
ready for shipping in 24
h

William Optics
Vixen Style Mounting Base
$ 45.90
ready for shipping in 3-5
weeks