To continue the flurry of news from Niantic and Nintendo, Nintendo of America just announced via Twitter that the Pokémon GO Plus device will become available on September 16, and as stated during E3, it will be priced at $34.99. 

According to Pokémon GO's official website the Plus connects to smart phones via low energy Bluetooth and notifies players about in-game events such as, nearby Pokémon and PokéStops. Whenever a player is in range of a PokéStop the Plus will begin to blink and vibrate, users can then press the big button in the middle to collect items.

In the case of a wild Pokémon being nearby, the device will flash and vibrate and users can then press the center button to throw a Poké Ball. This, however, can only be done with previously caught Pokemon. If successful, the device will flash and vibrate once again.  

Based on these descriptions, how one differentiates between one notification and the other is still unclear, but the device looks like a simple enough, cheaper alternative to an Apple Watch. 

Pokémon GO Plus is compatible with iPhone 5/ 5c / 5s/ SE/ 6/ 6s/ 6 Plus/ 6s Plus devices as long as they have iOS Ver. 8-9 installed. Android device requirements include 2 GB RAM or more, Bluetooth Smart (Bluetooth Ver. 4.0 or higher), and will need to have Android Ver. 4.4-6.0 installed. 

For complete compatibility information visit this page.