1.7 MHz is a common frequency because it gives stable fine mist for water-based humidification without making the module difficult to drive.
At this frequency, the droplets are small enough for most cabinet, tank and room-humidification projects. Actual spread still depends on airflow and the water surface layout.
The transducer, PCB and driver should be treated as one set. Mixing parts from different suppliers may work during a short test but fail in long-hour use.
For special liquids, high temperature water, or very compact tanks, confirm the liquid condition and installation space before choosing the module.
Project note: For normal water humidification projects, 1.7 MHz is usually a safe starting point. Final confirmation should be based on tank design and working hours.
