The Pokemon GO Plus is a device that allows you stay current with the game without actually being on your smart phone. It looks like a bracelet or watch and connects wirelessly via Bluetooth settings. It is low energy and gives a special alert if there are Pokemon nearby making use of an LED and vibration. It will also alert you of other game events.
If you are within range of a Pokestop, the device will light up and begin to vibrate. At this time, you will press the Pokemon Go Plus button to search for items. If you find them, tapping on them will add them to your inventory.
If a Pokemon is near by you, the device will flash green as an alert. If close enough, you can press the Pokemon Go Plus button to throw the Pokeball. However, you will only be able to use this device to throw the Pokeball if you have caught this particular Pokemon before. Once captured, the device will flash and vibrate again to let you know that you were successful in your capture.
It was available at Gamestop for preorder, but quickly sold out. It can at times be found on eBay, but going for upwards of three times the retail price.