Where can I get the Changers CO2 fit app? Changers Support June 25, 2017 10:00 Updated Follow The Changers CO2 fit app is available in a free version in the Google Play Store and the Apple App Store. Simply load onto the respective smartphone and get started. Related articles How can I connect my battery to the Internet? Which operating system version is supported? What does the Changers CO2 fit app cost? Comments 0 comments Article is closed for comments.