WIFI smart door detector can make us know doors and windows status, and no longer worry about whether you forget to close the doors and windows when you go out. Note The door detector Only make you know that the door is open or closed, and Just notify the door is opened or closed. The door window sensor detector security alarm can receive alarms Remotely, when doors and windows are opened by others, the door sensor will send out an alarm signal to your phone. The security alarm can be installed on door, window, cabinet and drawer etc. Easy to install, just need to use 3M glue to install, 2x AAA batteries powered (not included). When the battery power is low, it will remind you via APP, never worry about battery. Size Chart: L Door Sensor Size: approx. (LxWxH)7.2x3x1.9cm / 2.83x1.18x0.75 inch S Door Sensor Size: approx. (LxWxH)4.55x1.4x1.55cm / 1.79x0.55x0.61 inch Package Includes: 1 Piece L Door Sensor 1 Piece S Door Sensor Note: Please allow 1-3mm measuring deviation due to manual measurement. Due to the different monitor and light effect,the actual color of the item might be slightly different from the color showed on the pictures.Thank you!