Spiral Duct Diffusers were first introduced during the rustic exposed ceiling era in architectural design. Wherever air needs to leave duct-work and enter the conditioned space, a hole is cut in the duct, and a register is attached for directional air control and aesthetics. There are two ways to attach a virtually flat register to a round pipe (duct) and TRUaire Spiral Duct Diffusers proudly offer both models. The first is a Universal model, which utilizes thick foam material to form to the round duct. The second is the Saddle model, which saddles and forms to the pipes round shape without the use of foam. Both TRUaire Spiral Duct Diffusers feature solid steel construction. Options for both include single or double deflection blade configuration, white or aluminum finish, as well as an air scoop to divert a potion of the air stream out through the register. The Saddle Mounted Spiral Diffuser offers an exclusive option to add an Opposed blade damper.