The Arca Swiss rails allow for easy and fast adjustments. This 3 in 1 rail has a screw hole for your common camera tripod adapter. It also has the Arca Swiss rail which allows you to easily slide your gun back and forth. If you also have a picatinny bipod, there's also a picatinny rail in the front.
Recommend the Extended Dust Cap st0019 with this product as well.
Overall, it's a well versed rail for the FX Impact