The Zacuto 3in Z-Rail works with any of our Z-Rail accessories such as the Recoil Top Handle and any Z-rail mount . It is compatible with the RED Epic/Scarlet, the C300/C500 (with Helmet), the Black Magic Camera and others. It attaches via (2) ¼" 20 screws (included) that are spaced 3/8" screw center to center at their closest to 2" 5/32" at their furthest. The 3in Z-Rail can be used on a second camera so you can quick release any of the Z-rail accessories mentioned above back and forth between cameras. You can add our Z-Rail Slide Mount for multiple accessory mount options.