I connected it to my smartphone once and put it on my wrist. Returns are not accepted to prevent any issues. Smartwatch for running Polar Pacer GPS Returns are not accepted to prevent any issues. Heart rate measurement: 3 colors, 10 LEDs (optical heart rate sensor) Main functions: Wrist-based heart rate measurement, GPS (compatible with Michibiki), auto/manual lap measurement, running/walking test, displays energy consumption by three major nutrients, nutrition reminder, activity tracking (steps, distance, calories burned, etc.), sleep and autonomic nerve measurement, smart notifications (incoming calls/notifications), music control, weather forecast, water resistance 50WR Main uses: Running, trail running, outdoor activities, walking, strength training, fitness, swimming, etc. Operation: Button operation Size: 45 x 45 x 11.5 mm / Weight: 40g / Wrist circumference: 125-220 mm Compatible with iPhone / Compatible with Android