WhisperGreen Select's customization features really kick in with a set of patented Plug 'N Play® modules that give you the flexibility to design the perfect fan in advance, or on the fly, for a variety of ventilation applications. With our unique Plug 'N Play modules, you can choose up to three extra features. The first snap-in slot is designed for the Multi-Speed (0, 30 to 110 CFM) module with high/low delay timer. The two remaining slots can accommodate the SmartAction® Motion Sensor, Condensation Sensor or NiteGlo® LED night Light.