ACCURATE HEART RATE MONITOR - Optical heart rate technology provides accurate heart rate, calories burned, distance, speed, and pace tracking. BLE4.0 & ANT+ DUAL MODE - Supports both Bluetooth and ANT+ connectivity, compatible with most Bluetooth Smart and ANT+ enabled devices including fitness watches, smartphones, tablets, and gym equipment. IP67 WATER RESISTANT - Suitable for handwashing, household tasks, and use in the rain. Not suitable for swimming or bathing. COMFORTABLE ARMBAND - Lightweight and breathable design fits securely and comfortably on the arm, offering a more comfortable alternative to chest straps. APP COMPATIBILITY - Works with popular smartphone apps such as Wahoo Fitness, Zwift, Runtastic, Runkeeper, UA Record, Endomondo, Peloton, Map My Run, Komoot, and Nike Run Club.