Compact GPS Sport Watch with Optional Heart Rate From the Training ExpertsIntroducing the new Polar M400 GPS Fitness Watch with optional Heart Rate Monitor and built in GPS. The M400 activity tracker brings together style, performance & comfort – with an exceptional blend of a sporty design with advanced training and activity tracking. With the M400 you can easily monitor your speed, pace, distance & monitors heart rate while having real time training guidance and goals. The M400 also tracks 24/7 activity & sleep, providing you with a full view of your day. Incorporating the best of fitness & activity tracking, with true training intelligence you've come to love from Polar.""Please note that some watches may not have the port cover due to a rolling change per the manufacturer.""Quick Specs- 24/7 activity tracking- Activity goal and activity benefit- Inactivity alert- Sleep duration and quality- Built-in GPS- Fitness test (heart rate sensor required)- Heart rate with Polar H7 heart rate sensor(optional)- Personal best rewards after training- Training feedback- Standard micro USB charging- Polar Flow web service and app- MyFitnessPal integration (iOS only)Please use the drop down menu's to select between the optional heart rate transmitter.The M400 tracks 24/7 activity & sleep, calculates the number of calories expended in each training and during the day.