Plastic Grille Box
Plastic grille boxes are the most cost effective way to connect a square ceiling grille to round ductwork These robust thermoformed boxes are manufactured with a top entry spigot and a 25mm flange. The spigot is stepped into 2 or 3 different standard duct sizes (see size table below). To select one of the two larger sizes, simply cut the smaller spigots off with a hacksaw or knife.
