Project packs are ideal for contractors and builders who have yet to pick out the final product. With the housing for the fan sold separately from the grille and motor, contractors are able to continue with construction and not have to worry about damaging, losing or storing the product. Once all construction is complete, the purchase of a finish pack (grilles and motor/blower wheels) can be made to add the finishing touches to the room. The 6884H housing pack consists of 18 housings with 4 in duct connectors attached. Pair it with the 1688F, 1671F, E0F70, 696RNB or 696RB finish packs to create 4 in ducted economy fans. Note: Three finish packs will need to be purchased to supplement one 6884H, as the finish packs come as 6-packs, and the 6884H is an 18-pack.