Simucube extensions come in 120mm, 140mm, 160mm, 180 and 200mm lengths.
When choosing the size remember that you want to be as close as possible to your screen to take the full advantage of the screen real estate so the screens cover your entire peripheral vision (if you have 27" 32" triple screen setup).
We offer different sizes because there are a lot of rigs and screen types out there varying in sizes and thickness, larger length FOV extensions are usually for people using larger TV screens/projectors or are searching for personalized driver ergonomics.
120-140mm extension should cover all 32" screens for best immersion.
You can configure your Simucube extension to be used with your Simucube QR Adapter supplied with the base, or standard 70mm 6 bolt Adapter so you can use any QR system you prefer. It can even be configured to be used with Fanatec QR2 system