Stack Starter Kit, 1 hub and 2 BR30 Downlights, Works with Alexa Works with Amazon Alexa to support dimming through voice control (Hub required and included, Alexa device sold separately.) Stack lights automatically respond to your presence - on when you're there and off when you're not Using ambient light sensors, stack lights automatically dim with sunlight, saving money and energy Starter kit contains 1 hub and 2 downlights (BR30), which fit most common recessed can fixtures Stack lights support circadian wellness with automatic color temperature shifting from 2700k - 6500k