As promised, Fitbit has launched its mobile app for Windows Phone devices. The version the maker of the popular fitness band launched is made to sing along Windows Phone 8.1 smartphones, and will not work with the majority of devices running Windows Phone 8.

The Windows Phone app will also support all Fitbit fitness trackers, including the Zip, One, Flex and Force, connecting to them via Bluetooth 4.0.Microsoft and its partners have yet to update most of the phones to the latest version of the platform. Nokia, now part of Microsoft, has started rolling out firmware updates for some of its models, but the process has yet to include all parts of the world.

Like that’s the case with Fitbit’s app for iOS and Android, the Windows Phone version will also support all Fitbit fitness trackers, including the Zip, One, Flex and Force, connecting to them via Bluetooth 4.0. Fitbit has apparently worked closely with Microsoft to optimize the app that includes several platform-specific features such as Live Tiles and background syncing.

Finally, to celebrate the Fitbit’s arrival to the platform, the Redmond giant is offering the Fitbit Flex bundled with the Nokia Lumia 635. Said mid-range smartphone is available in two variants, one made to sing along AT&T’s and the other with T-Mobile’s network. The former is going for $148.95 while the latter costs $30 more. Both devices are available from Microsoft’s online, and brick and mortar shops. The deal is valid through September 1st or until the Flex goes out of stock.