Elgato Eve Door and Window Sensor

If you worry about open doors and windows, this gadget from Elgato (available from apple.com) can keep your stress levels down. This unobtrusive sensor is easily installed and, once synced with the Elgato app, can tell you the status of the door or window it’s monitoring. You can even use it to automate other smart devices, such as those that turn on lights as soon as you open the front door.