An intelligent self-balancing downstream device (e.g., air fixture or diffuser) that can obtain accurate flow measurements that can be used to perform the self-balancing in situ and during operation to satisfy a set point. The downstream device may be controllable by a single software system or network accessible locally on site or remotely off site. The downstream device can operate in a single zone or be coupled with multiple like apparatuses for multi-zone operation. It is a high turndown ratio and self-balances, which can allow for continuous commissioning with built-in fault diagnostic systems and that may be used as a supply, return, or exhaust system, or a combination thereof. The downstream device can include multi-stage airflow control systems that operate progressively based on unique actuation mechanisms and/or algorithms that allow for precise flow control and feedback to self-balance and commission the system.