Supply air outlets, terminal units, chilled beams, fan-coil units, and air curtain units introduce air into a conditioned space to obtain a desired indoor atmospheric environment. Return and exhaust air are removed from a space through return and exhaust inlets (inlet and outlet are defined relative to the duct system and not the room). This chapter describes this equipment, details its proper use, and is intended to help HVAC designers select room air distribution equipment applicable to the air distribution methods outlined in Chapter 58 of the 2023 ASHRAE Handbook -- HVAC Applications. SYSTEMS OVERVIEW SYSTEM CLASSIFICATIONS Fully Mixed Systems Fully Stratified Systems Partially Mixed Systems EQUIPMENT Supply Air Outlets Return and Exhaust Air Inlets Grilles Nozzles and Drum Louvers Diffusers Terminal Units Fan-Coil Units Chilled Beams Air Curtain Units