Airflow systems manage where cooled air actually goes inside and around a rack: rack-mounted fan and duct units that pull hot exhaust out of the cabinet, airflow management panels and ducts that stop hot air from recirculating to equipment intakes, and the accessories that adapt racks to hot-aisle and cold-aisle design. Cooling capacity that never reaches the intake is capacity wasted - airflow hardware is how it gets there.
Diagnose before buying: hot spots at the top of a cabinet call for exhaust management, mixed intake temperatures across a row call for containment and blanking, and a sealed closet may need ducted exhaust more than more cooling. Match units to the rack brand and depth - much of this hardware is family-specific - and treat blanking panels as the cheapest airflow fix that exists. Plan fan units' power like any other rack device. COLAMCO quotes airflow management with the racks and cooling it supports for business, government, and education equipment rooms.