An ARRIS RAIL offcut, at least 1.2m long (Wolverton MK12)

An Arris rail is the horizontal piece of wood (with a triangular cross-section) that holds together the vertical wooden slats of a fence. 75mm x 75mm cross-section. This is to go on top of our gate frame, which is tempted to go rotten if we don't put something above it to 'cap it'. Many thanks.