FAS Clamp has dovetailed bottom and lever-release top clamp.

1. "Fore-Aft Sliding" clamp slides along dovetail of any Really Right Stuff rail or camera bar to provide adjustable fore/aft travel.
2. Unique bottom index marker allows for exact and repeatable positioning.
3. Slide lock-knob locks clamp into position.
4. Clamp channel runs left/right and accomodates plates with left/right dovetail orientation (most camera body plates, but not lens plates); clamp cannot be rotated to change orientation.
5. NOTE: Choose a Lever Release clamp ONLY if you have quick release plates from Really Right Stuff or Wimberley. Lever Release clamp are not user-adjustable, and different manufacturers may follow different standards when producing Arca-Swiss compatible plates. Specifically, our Lever Release clamps do not work with plates from Markins, AcraTech, Arca-Swiss, and some Kirk plates–the dovetails are too shallow. Choose a screw-knob clamp if you have plates OTHER than those from RRS or Wimberley.

Lever Release Clamp User Manual