NET-O Electronic Whistle [3 Levels, 3 Whistle Sounds] New Model, Includes AAA Battery (Blue).This is a product from a Japan Self-Defense Forces bidding project (Eastern Army Accounting Unit). The new model is an evolution of the previous model, prioritizing ease of use. [Ranked #1 on Amazon's whistle ranking as of March 3, 2018] [Power Source] Upgraded from button batteries to AAA batteries! Battery replacement is also easier. [Volume] Features high, medium, and low volume settings for versatile