Summary These are a must for anybody laying Flexible track makes the job so easy, and gives nice smooth curves. This is a clamp that grabs the rails tight so that flexible track can be easily held in the curve shape while you pin or glue the track section in place. Not much pressure is required to clamp the rails to stop them moving. I have a set of 4 for making complex curves. Post-Printing FITTING NUTS I used 3mm cap heads 30 mm long, and to set the nuts into the hex I used a soldering iron to bed the nuts in