The latest version of the Pokemon Go app on iOS and Android supports the new Pokemon Go Plus device, which costs $35 in the US, £35 in the UK or AU$50 in Australia.
The Pokemon Go Plus can be used on its own or while attached to an included wristband.
The gadget can be worn anywhere from the wrist with an included strap, or attached to a pocket using a clip.
The Settings menu in the Pokemon Go app will have a section that lets you sync up with the Pokemon Go Plus device.
When synced, a Pokemon Go Plus icon will appear on the app's screen.
The device will vibrate and turn green when you are near a Pokemon that you have caught before, and yellow when it's a creature you haven't caught before. Tap the button to try to catch it, and if it blinks several colors, then you have succeeded. If it turns red, then you failed.
When the device glows blue, it means you are at a PokeStop and can tap the button to collect Pokeballs, Berries and Potions among other possible items.
You can find out what Pokemon you caught using the device by checking the Journal section of the app.
The Pokemon Go Plus can clip nicely to a jacket.