A Note About Compatibility
There are a number of companies that sell gear based on the Arca-Swiss dovetail rail. In addition to Really Right Stuff, companies such as Wimberley, Markins, AcraTech, Foba, Novoflex, and Kirk sell gear that is commonly marketed as "Arca-Swiss style" or "Arca-type" or "Arca-Swiss compatible. Arcs-Swiss has never published a standard, so we developed our own and distributed it within the industry. In general, most of this gear is cross-compatible (but many Novoflex plates do not fit our screw-knob style clamps). For example, a Really Right Stuff L-plate will work just fine with the quick-release clamp on your Markins ballhead. And your Wimberley lens plates will work great with any Really Right Stuff clamp and ballhead. An exception to this is our lever-release clamp.
WARNING ABOUT OUR LEVER-RELEASE CLAMPS
Due to wide variations in other brands of Arca-Swiss compatible plates, we recommend using our lever-release clamps only with Really Right Stuff or Wimberley brand quick-release plates. If you own other brand plates, see this note about our plate exchange policy.
Our lever-release clamps are not user adjustable, so the plate that you use in our lever-release clamp has to be EXACTLY the right width. Only Really Right Stuff and Wimberley build plates to the same exacting tolerances. But screw-knob style clamps are much more forgiving of slight differences in plate width since you control the clamp jaws by turning the screw. So most Arca-Swiss style quick-release plates will work in most screw-knob versions of Arca-Swiss style clamps. Warning: many Novoflex plates do not work even in our screw-knob style plates.
To summarize: all Really Right Stuff plates and rails will work in all screw-knob versions of Arca-Swiss style clamps. This includes screw-knob versions of Arca-Swiss style clamps from Markins, AcraTech, Arca-Swiss, and Kirk. BUT only Really Right Stuff and Wimberley plates and rails are guaranteed to work with Really Right Stuff lever-release clamps.