Key specifications include Input Voltage Range, Rated Power (Watts), and Control Method (e.g., Sine Wave vs. Square Wave control). Sine wave controllers are preferred for premium fans as they provide lower noise levels and smoother rotation. Additionally, check for protection features such as Over-Current Protection (OCP), Over-Voltage Protection (OVP), Locked-Rotor Protection, and Thermal Shutdown. For smart fans, ensure the PCBA supports PWM speed regulation or wireless integration like Wi-Fi/Bluetooth/Tuya modules.