The Sunwayfoto DPG-3016R Stereography Rail is an Arca-type compatible rail that also works with Really Right Stuff lever clamps. It can be used to mount two cameras on a single tripod. You can adjust the camera forward and back without moving the tripod, and you can also accurately find the nodal point for panoramic photography. It has six 1/4"-20 sockets and one 3/8"-16 socket for flexibility. There are M3 holes in twelve different positions on the upper rail for mounting safety stop screws.