Check the frequency the cleaner operates at. A true ultrasonic cleaner operates in the range of 20 to 400 khz (20,000 to 400,000 Hz). These provide true ultrasonic cleaning. Many cheaper models operate at a much lower frequency, simply vibrating the objects, and are ineffective cleaners. The higher the frequency the smaller the cavitation bubbles and the smaller the intricacies that can be cleaned. Beware though, a true ultrasonic cleaner may be a little hard on silica wicks.