I am trying to find a sliding rail to place on top of a saw horse. I want to slide a small platform along the rail, and I would like to secure the platform at a specified position by tightening a nut and bolt. Does anyone here have an idea of where do find what I am describing? Ideally, I would like to slide the platform freely along the rail while being able to secure the platform by tightening the nut/bolt combo that runs through the sliding platform and the rail. Any help would be greatly appreciated.