When Pebble announced the Time smartwatch, it said companies will be able to expand its functionality with third-party add-ons. Well, first such health-based add-on (as far as we know) has been unveiled, and it’s currently raising funds at Kickstarter. This, if you recall, is also the place where Pebble launched its products.

Called Vu Pulse, the smart accessory attaches to and surrounds the Pebble Time to add heart rate and fitness tracking sensors to the mix. When in “passive mode,” the device will monitor user’s heart rate every 30 seconds to help save Pebble’s battery. On the other hand, when the “active mode” is turned on — during workouts — Vu Pulse will increase heart rate reading frequency to every 10 seconds.

The companion app, available for iPhone and Android, will capture all of the usual data points you would expect from a standard activity tracker with built-in heart rate monitor. Automatic activity/sport detection isn’t mentioned, though.

Vu Pulse was designed by the company called Tylt; the device is currently up for pre-order for $44. Beta backers will get it in June, with the final product tentatively slated to deliver in August.