I put Head/Tyrolia PRX12 bindings and PowerRails on a pair of flat skis. (PRX has more delta than PRD; more delta works for me.) The rail has no boot-center marking. I had to put the bindings on the bare rail, put the boot in, transfer the boot center mark to the rail. Put the rail on the ski, match the center line, mark the 8 screw holes, then I could drill & tap the screw holes. The PowerRail has 2 fixed mount screws and 6 that allow longitudinal float for flex purposes. Anyway, it worked out well, took a lot of time, and was interesting to me to do it.