Abstract: A plenum slot diffuser includes a plenum box having five walls formed by joining edges of a C-shaped bracket having first, second, and third walls of the five walls with additional edges of an L-shaped bracket having fourth and fifth walls of the fives walls. An air input opening of the plenum box is disposed in one of the five walls and is configured to be coupled to a duct, and an open end of the plenum box defines an air output opening.