Two-Piece Wifi Door Window Sensor Detector Set: Smart Door Sensors For Home And Product Details APP ALERTS ON YOUR PHONE: Wifi door sensor, "Tuya Smart" or "Smart Life" APP control. No hub required and No fees charge. When door/window is opened or closed, the sensor will push instant notification to your smartphone immediately. You can check your house on APP whatever where you are. DOOR ALARM COMPATIBLE WITH ALEXA,GOOGLE HOME: Smart door window alarm works with Alexa and Google Home. Support voice control by Google and Alexa. Alexa/Google is able to answer the question ?Is the door open/closed?? WIRELESS MAGNETIC SENSOR--EASY INSTALLATION: Without tools, easily setup wifi window alarms for home in minutes, just use 3M glue to install, firm and durable.The two arrows are opposite,the distance between the two components should be as close as possible,and the closest distance should not affect the opening/closing of the door or window. LONG-LASTING PERFORMANCE LOW POWER WARNING: Door open alert wireless door sensor powered by 2*AAA batteries(Included), working time can last for one year without to replace the battery. When the battery is running low, it will automatically push messages through APP to remind you to change battery, never worry about running out of battery. UNIVERSAL COMPATIBILITY QUALITY GUARANTEE: Install the alarm sensor not only on front doors or windows, but also on garage doors, liquor cabinets, front gate, safety deposit box, pet doors and more. And we will offer you a replacement or refund if you have any problems with your door open alert wireless door sensor. Payment We accept PayPal and credit cards via PayPal. Taxes - US We collect sales tax, as required by law. Shipping We make every effort of shipping within 3 business day of payment clearing. The estimated delivery time is 2 - 5 business days from the shipping date. Policies If you do need to return your item, please contact us via email (you will receive an email when your product ships with additional details - Subject: Important information about your purchase). You will then be provided with a return shipping label and packing slip. Pack the item carefully. Include the packing slip, apply the shipping label, and return the item within 30 business days of the date you request a return, or your return will be canceled. Once we receive your order we will inspect the return. Please allow up to 5 business days of receiving the returned item for your refund.