"Concealed Duct Fan" refers to a type of fan designed for installation within the ductwork of a building, providing ventilation, air circulation, or air conditioning functions without taking up indoor space. These fans are typically compact, low-noise, and efficient in design to fit within the limited space of ductwork while ensuring necessary airflow without disrupting the indoor layout. This design helps maintain a clean indoor environment, offering the required functionality for comfortable indoor climates while visually preserving a neat and minimalist appearance. Such fans are commonly used in commercial buildings, offices, and other spaces requiring ventilation systems.