Some motors use capacitors, which are an electrical componant necessary for motor operation. Most of the direct-drive motors sold on our site require a capacitor, which needs to be purchased in addition to the motor. There are different sized capacitors for different motors. Capacitors are rated in MFD numbers (Microfareds). Each motor shows what MFD capacitor is required. First check the motor to see what MFD capcitor is required, then select here the correct MFD capacitor for your new motor.