Android has a nice feature named "Smartlock" that does not lock your phone when you are near a specific Bluetooth device. When you are at home, you can tie it to some device in your home that never goes off. When you are traveling, is there some cheap Bluetooth device that you could put on your keychain that might last a month on batteries that would just flag the phone that you are nearby? I realize you can use a Bluetooth headset for this purpose, but sometimes you want to turn the headset off. And you need to check a notification on the phone and do not want to hassle with a PIN or other authentication. I guess some people use a Bluetooth watch for this purpose, but there is another device I would have to charge constantly. I want simplicity.