Xiaomi CEO teases next version of its best-selling $15 fitness band.

Fitbits and the Apple Watch may be the most well-known wearables around, but Xiaomi's dirt cheap Mi Bands dominated the wearable market last year, coming in second to Fitbit, which was the No. 1 wearable vendor, according to the most recent IDC report.

Thanks to its $15 price, the Mi Band has become immensely popular, especially in Asia. The fitness tracker moved more than 10 million units last year. Xiaomi's now ready to unveil the next model.

At a recent Chinese wearable conference, Xiaomi CEO Lei Jun posted a photo of himself sporting the Mi Band 2, the successor to the Mi Band.

Details on the Mi Band 2 are scant, but we can clearly see the wearable has an display and a round button on the top. (The Mi Band is rather simple and has no screen or button, which helped keep the price so low.) Its larger design should also mean it'll include features like a heart rate sensor from the equally cheap Mi Band Pulse.

Xiaomi is holding an event on May 10 in Beijing to unveil the Mi Max, a phablet with a rumored 6.4-inch screen. It's likely we'll learn more about the Mi Band 2 at then