The VPA-FF is a double sided female to female dovetail clamp. Each side clamps onto Vixen “V” Series dovetail bars, which are the standard dovetail bars found on most Sky-Watcher, Celestron and other brands. These are different from the "Synta" dovetails (which are narrower) and the "Losmandy" or "CGE" dovetails which are wider. Vixen dovetails are approximately 1.75" wide (44.5mm).