Three-Way Smart Wifi Dimmer Light Switch (Wf31S), In-Wall, No Hub Needed, Works IMPORTANT: Must have Neutral Wire for this to work, please check your wiring prior to purchasing. Affordable 3-Way Solution: No special companion switch needed. Work with regular 3-way on/off switch for 2 locations control, does not work with a smart switch or a dimmer switch. Remote operation: Control the device remotely with your smartphone when connected to 2.4G wifi network, for scheduling, dimming and ON/OFF operation from anywhere. Voice Control: Works with Amazon Alexa/ Google Assistant (sold separately) to enable voice control. High Quality: Built with sturdy aluminum plate and fireproof plastic, rust-proof, heat faster, more sturdy. Latest Upgrade: The smart switch shell depth is reduced by 20% size compared to previous models, to fitting in more switch boxes. The latest user manual has been updated on the product detail page. Only support single-pole and 3-way circuit, not support 4-way circuit, Not suitable for fans. Only support 2.4 G Wifi.