Applied Roma XL Channel to underside of my deck handrail. Ran the low voltage cable thru posts and then thru the bottom of the handrail. Cut Roma track to length for each opening and then using 3M Heavy Duty outdoor double faced tape attached to underside of rail. Installed LED string lights (200+ connections across 54' of handrails). Custom cut "black" diffuser cover to fit each track. Have LED lights on a dimmer switch. When lights are off everything showing is black. Which makes tracks invisible to the eye. Looks absolutely fantastic, very high end look. Important thing is to run the low voltage wiring during handrail assembly. Could not be happier with the result.