Works independently without real-time connection to a smartphone. Designed with color screen and built-in memory to store up to 100 readings in the device. Easy to use and compact size to record 30 seconds' ECG and heart rate between your hands anytime anywhere. Keep track of your health regularly and share data with your doctor without subscription or limitation. Record first, sync later to the provided EMAY app and PC program for bigger review and easy sharing of your data. Different ways of recording (Hand-to-Hand, Hand-to-Chest, Hand-to-Leg) to give you a thorough picture and higher accuracy for better reference. Local customer service team in California to ensure your satisfaction. We don't recommend to use the device with pacemaker and ICDs. This device is intended for OTC (Over-the-counter) use. Model EMG-20 Package content : One EKG Monitor, One USB Cable, One User Manual . Compatible with : iOS 10 or later , Android 7 or later , Windows 7 or later , macOS 10.12 or later Brand new in sealed box