Works with Alexa for voice control (Alexa device sold separately).. 100% Wire-free - Lets you discreetly place cameras indoors or outdoors. Untethered mobile security- Supports 3G and 4G-LTE wireless connections. Night Vision- Enhanced night vision capability lets you see clearly even in the dark. Weather-resistant - Place them anywhere-indoors or out.Night vision:850 nm LEDs,illuminates upto 25 ft. Local video and audio storage- Built-in SD card slot allows for local backup storage in the event of Internet interruption. 2-way audio - Push-to-talk capability, so you can listen in and talk back. Free cloud recordings- Rolling 7-day free cloud recordings. Arlo Smart adds powerful intelligence to your Arlo cameras. Customize alerts to detect people, specific zones, and contact emergency responders right from your smartphone's lock screen (optional service, includes 1-month trial).720p resolution.