The MZ-3 USB Cable Charger keeps you charged and ready to go. The MZ-3 charger is built to charge through your USB computer port only. One full charge keeps you going for up to six months. That’s a lot of burpees... Features Connect the USB charging cable to the back of your MZ-3 and charge for up to 45 minutes. To protect your battery we don’t recommend using a 9 volt charger - plug it into the USB port in your computer instead. A full charge lasts up to 6 months - depending on how hard you go. Battery charging lights: Pulsing red = no battery. Pulsing green = fully charged. You’ll get a handy notification when you have less than 20% battery. You can also check the battery level in the Workout screen whenever you like. Compatibility Myzone MZ-3 Heart Rate Monitor