Where can I get the Changers CO2 fit app? Changers Support December 15, 2016 09:48 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? How does the app measure the kilometers? Who can use the CO2 fit app? Comments 0 comments Article is closed for comments.