The Extreme is the latest update on the flipping lens adapter systems by Letus. Unlike previous versions, the Extreme is built on a higher quality prism optical array. The adapter is made up of milled aluminum with a hard anodized black finish. Instead of the usual configuration, you can opt to go for the upper configuration, though the reviewer noted that the flip unit comes in contact with the built-in camera microphone on the Sony EX1 and FX1 due to its size. It comes in a pre-configured oscillation frequency that is not user adjustable. If you need to use a different style still lens mounts, it only takes a few minutes, offering an array of lens mount options. However, the reviewer summed up by making it clear that the process of setting up and configuring the Letus Extreme becomes a balancing act between enough sharpness and an evenly illuminated frame. When properly configured, you get excellent resolution, edge sharpness and virtually no vignetting.