DieselOn is a free lifestyle application developed by Fossil Group Inc. that serves as a companion app for Diesel smartwatches. The app offers a wide range of features related to fitness and connectivity to your smartphone. It is compatible with Gen 6 wearOS and Hybrid smartwatches. With DieselOn, you can pair and activate all Diesel smartwatches with your smartphone and get real-time notifications of incoming calls, messages, and other applications on your watch. Additionally, you can find your smartwatches based on the last location of your device, track your daily fitness activities, including steps, distance, calories burned, and sleep quality. The app also allows you to monitor your heart rate and blood oxygen level, and connect to voice assistant services. Overall, DieselOn is a comprehensive companion app that enhances the smartwatch experience and offers a range of features to keep you connected and on track with your fitness goals.