From Manufacturer
Acratech's Swift Clamp provides an easy way to connect a camera with an Arca-Swiss-compatible quick-release plate to your sling strap, using the built-in eye on the back side of the clamp. The Swift Clamp's lever has a safety clamp that locks automatically when you close the lever.
Connects Arca-Swiss-compatible QR plate to a sling strap
The Swift Clamp's lever has a built-in safety clamp that locks when the lever is closed