All you need is a 10mm hole drilled where you want to install them, the model is held in place with a special mounting cap (supplied).
Train-Tech LC10 Level Crossing Barrier Set with Light & Sound Single OO Gauge
Train-Tech LC10P Level Crossing Barrier Set with Light & Sound (Pair) OO Gauge
Train Tech Single Level Crossing Barrier with Light & Sound (OO) HO/OO Gauge
Train Tech Lighting Effect Level Crossing Barrier Lights w/ Sound N/HO/OO Gauge
Train Tech Lighting Effect - Level Crossing Barrier Lights N/HO/OO Gauge TTLFX1
Train Tech CN10 N Gauge Single Level Crossing Barrier Set With Lights & Sound