Length 126HP = 126x 5,08 = 640,08 + margin* = 641mm
Due to years of building experience, we cut our rails with a little length margin*.
Why? Not all modules have an exact HP width so it can happen that when you cut the rails to the exact 126HP dimension, not all your modules will fit. The threaded strips/inserts have an exact 126HP size, so you can’t go wrong installing your modules. Trust us, we’ve been there:)