Telescopes and accessories are often equipped with a prism rail - also called a dovetail bar. This rail can be attached firmly by means of a dovetail clamp to, for example, an astronomical mount.
Two standards have been established for the rails: 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.
Accordingly, there are dovetail clamps for Vixen or Losmandy rails. Dual dovetail clamps can accommodate both sizes.

ADM
Prism clamp/adaptors for Skywatcher StarAdventurer GTi
$ 114.00
ready for shipping in 24
h

PrimaLuceLab
PLUS Vixen / Losmandy prism clamp
$ 78.00
ready for shipping in 24
h

Artesky
Vixen-Style Prism clamp 150mm
$ 57.00
ready for shipping in 24
h

ADM
VSAD-GP Vixen Great Polaris
$ 253.00
ready for shipping in 3-5
weeks

Bresser
Dovetail clamp Messier Vixen-Style
$ 44.90
ready for shipping in 24
h

Omegon
Dual prism clamp (Losmandy- and Vixen-Style)
$ 119.00
ready for shipping in 24
h

PrimaLuceLab
PLUS Vixen /Losmandy prism clamp, large
$ 166.00
ready for shipping in 24
h

Artesky
Vixen-Style Prism clamp 80mm
$ 49.90
ready for shipping in 24
h

ADM
Dual Vixen/Losmandy Prism Clamp for Celestron AVX
$ 370.00
ready for shipping in 24
h

ASToptics
80MM DX LOSMANDY LEVEL DOVETAIL CLAMP
$ 137.00
ready for shipping in 24
h

William Optics
Vixen-Style 90mm Prism Clamp
$ 114.00
ready for shipping in 24
h

PegasusAstro
Saddle Powerbox NYX-101
$ 520.00
ready for shipping in 1-2
weeks

iOptron
Secondary Dovetail Saddle
RRP:
$ 148.00
Our price:
$ 124.00
ready for shipping in 24
h

ASToptics
150MM DX LOSMANDY LEVEL DOVETAIL CLAMP
$ 228.00
ready for shipping in 24
h

ASToptics
DX VIXEN/LOSMANDY CLAMP, 150MM
$ 263.00
ready for shipping in 24
h

ADM
Dual Skywatcher AZ-5
$ 148.00
ready for shipping in 24
h

TS Optics
Vixen-Style Premium Prism Clamp
$ 62.00
ready for shipping in 3-7
days

ADM
Dual iOptron GEM28 / CEM26
$ 331.00
ready for shipping in 3-5
weeks

Artesky
Premium Losmandy-Style 255mm Prism Clamp
$ 114.00
ready for shipping in 24
h

ADM
Prism clamp for Skywatcher AZ-GTI Mount
$ 136.00
ready for shipping in 24
h

ADM
Prism clamp with Vixen-Losmandy adaptor
$ 273.00
ready for shipping in 3-5
weeks

ADM
DSAD-SP Prism clamp for Vixen Super Polaris
$ 253.00
ready for shipping in 3-5
weeks

Geoptik
Prism clamp, Losmandy-Style
$ 58.00
ready for shipping in 24
h

PegasusAstro
Universal Clamp
$ 171.00
ready for shipping in 1-2
weeks

PrimaLuceLab
Prism clamp PLUS Vixen/Losmandy Maxi
$ 227.00
ready for shipping in 24
h

Baader
Prism clamp, with handle, for Losmandy-style prism rail
$ 96.00
ready for shipping in 1-2
weeks

Artesky
Guidemount - ultra-compact Vixen GP level dual mount
$ 148.00
ready for shipping in 24
h

ADM
Dual Saddle Plate XL for Skywatcher EQ-6R PRO mount
$ 390.00
ready for shipping in 24
h

Geoptik
Losmandy to Vixen reducer
$ 114.00
ready for shipping in 3-5
weeks

Omegon
Premium clamp
$ 79.00
ready for shipping in 24
h

Losmandy
Vixen / prism clamp
RRP:
$ 114.00
Our price:
$ 104.00
ready for shipping in 24
h

ADM
VPA Synta-GP
$ 136.00
ready for shipping in 3-5
weeks

TS Optics
Prism clamp Premium Losmandy-Style
RRP:
$ 102.00
Our price:
$ 81.00
ready for shipping in 3-7
days

TS Optics
Adaptor Dovetail Clamp from Losmandy to Vixen Level
$ 160.00
ready for shipping in 3-7
days

Losmandy
Prism rail with two V/D prism clamps
RRP:
$ 680.00
Our price:
$ 457.00
ready for shipping in 24
h

PrimaLuceLab
PLUS Vixen/Losmandy with 1kg counterweight
$ 106.00
ready for shipping in 24
h