Microzone Clean-Ceil2 fan filter module. Provides particle-free air. The motor/impeller draws air from the surroundings, forces it through a pre-filter, then through a replaceable HEPA or ULPA filter. Designed to fit in standard clean room T-grid ceiling systems. Rated 99.99% efficient at 0.3 microns. External dimensions of 23 5/8” x 47 5/8” x 13 1/2”.