OO/HO Back to Back Brass Gauge 14.5mm DCC Concept DCG-BB145

, thenthis device from DCC Concepts will make it easy to check. If your model railway is OO or HO runningon 16. Gauge/scale: OO (1:76). Instead justplace this device between the wheels and if it is a snug fit then the back-to-back is set correctly!