Check it out:
Nintendo Pokemon Go Plus https://www.amazon.com/dp/B01H482N6E/ref=cm_sw_r_cp_api_UJc3xb1SC53P1
Additionally, an update has been made available which improves the Pokémon Go Plus experience
Trainers, Pokémon GO is being updated to version 0.37.1 for Android and 1.7.1 for iOS with minor fixes for the Pokémon GO Plus.
— Pokémon GO (@PokemonGoApp) September 16, 2016