BoxWave Cable Compatible With Polar M400.Micro USB DuraCable: Charging that lasts for years to come!The Micro USB DuraCable combines SYNC AND CHARGE capabilities into a single, durable, standard, low-cost cable for your M400! Standard USB 2.0 connector for easy syncing connectivity and charging compatibility. DUAL FUNCTION design replaces the cradle and makes traveling convenient.Durable BRAIDED NYLON construction prevents kinking and splitting. Rubberized grommet strain reliefs add durability.Micro USB DuraCable: Sync and charge with assured longevity!