The Blackmagic Design URSA Mini Pro B4 Mount replaces the mount on the Ursa Mini Pro to enable you to mount ENG-style B4 lenses on your camera. The mount features a locking lever and incorporates corrective optics that enable the use of a lens designed to work on a camera with three sensors and a prism, on the URSA Mini Pro, which is a single-sensor camera, without the image suffering from optical degradation.A shim kit is included to allow precise flange distance adjustment when installing this mount on your camera.