Garmin forerunner 645 musica super athletic watch built specifically for runners that provides advanced running dynamics, allows you to track your progress, pay on the go, listen to up to 500 songs, receive smart notifications and more.music playerto make your running kit as streamlined as possible garmin have built in a music playing system to the forerunner 645. Up to 500 songs can be stored onto the watch and easily played by syncing a pair of bluetooth headphones to the watch.tracking your running performancethe forerunner 645 has been purposefully built for runners and it uses gps and glonass to track your performance. The watch therefore follows your movements and shows you in real time analytics such as ground contact time balance, stride length, vertical ratio and more. There are also other tools that you can toggle such as the training status application which automatically evaluates your recent exercise history and performance features to let you know if your training is productive, peaking or overreaching.heart rate monitorfor further ways to view your performance the watch comes with a fully integrated wrist based heart rate monitor. Unlike other heart rate monitors that involve wearing a fiddly chest or arm based strap. Instead the wrist based heart rate monitor of the vivoactive accurately provides your heart rate in real time, all the time. This can give you key indications into your general fitness levels.connectivityfor further features and full customisation the watch can be connected to your smartphone device via bluetooth, ant and through wi fi that is built into the watch. You can use this connection to access the garmin connect app which your performance data will automatically upload to so that you can see your levels and analyse your progress over weeks, months, and years. You can also use the app to customise the watches display and create your own workouts. The connection also allows you to receive your phones notifications straight to your watch face for an extra level of convenience.garmin paystreamlining your running kit further youll never have to leave the house with your wallet again with the new garmin pay feature. This allows you to make contactless payments while youre out on the go.featuresstores and plays up to 500 songsup to 7 days of battery lifewrist based heart rate monitorprovides advanced running dynamicscomes with all new garmin paystores up to 200 hours of active datadisplay comes with 240x240 pixel displaywaterproof to 5atm levelconnects to your smartphone for additional optionsweighs 42.2gbuy garmin watches from chain reaction cycles, the world's largest online bike store.