A gauge can be used to accurately measure the tension on each cable, but with enough experience, you can actually pluck the cables as you tighten them while listening to the sound, just like tuning a guitar. This approach creates extremely even tension across all of the rails, leaving you with a railing system that lasts longer without warping or deflection. We also sight down the end posts while tensioning the cables, and we always go through the tensioning process at least twice.