A tubular passage for poured concrete decks has an intumescent tube held in a two-part, clamshell base. First and second, spaced apart, funnel shaped, diaphragm seals are connected to a first tubular passage or an adjustable length tubular extension. A cap for closing either tube has an inclined outer surface to form a beveled entrance to the passage in the concrete. An aerator box may be connected to the base. Hinged ends on the base allow the shape and length of support to be altered.