1. Tuya ZigBee Hub wireless gateway is a must-have for SOS sensors and ZigBee smart products. It has been proven to be and control center of smart homes. It plays an irreplaceable role for all ZigBee products and realizes the connection of all smart homes. After adding the Hub to Smart Life / Tuya APP just add the sensor to the ZigBee Hub. 2. One-click alarm for emergency help. The Smart Life Tuya App is compatible with smartphone push notifications and can receive alarm information from smartphone sensors anytime and anywhere. 3. Mini design wide range of applications suitable for the elderly and children especially for sending with just one click. There are no complicated actions or buttons. 4. DIY compatible control: Supports DIY sensors to intelligently connect with other smart devices to detect on/off motion water fire and other smart scenes. 5. Transmit frequency 100dBm battery powered; wear it anywhere with a rope; use it with a zigbee gateway hub to define the working mode of the scene anytime and anywhere. This product must be used with Zigbee Gateway (not included). Without Zigbee Gateway it will not work. Technical data: Battery: CR2032 (battery included) Working temperature: -20 -60 Operating humidity 95% RH (non-condensing) Transmission frequency: 10dBm Emission current: 45mA average 1~2mA Quiescent current: 2~3uA Launch distance: 100m + (open space) Wireless frequency: Zigbee 3.0 The appearance and color of different batches of products may be different which will not affect the use. Colour:White Material:plastic Package Contents: 1 x ZigBee Devices Button Only the above package content other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.