The use of smartphones for arrhythmia monitoring is another leap for ECG utilization and arrhythmia detection - effectively taking the technology to any smartphone user. Smart wearable technology, while very common, is limited mostly to activity tracking and exercise motivation. Rhythm strip generating smartphone products (Kardia Mobile by AliveCor and ECG Check by Cardiac Designs) are more powerful at arrhythmia detection than wearable monitors. These products, which have been studied in a variety of situations, rely on an external device with metal sensors to create a rhythm strip, which is usually Lead I. A different subset of smartphone products use photoplethysmography through a phone camera and light to detect atrial fibrillation. Together, these products are creating a paradigm shift in rhythm detection and monitoring.