(Pocket-lint) - Xiaomi's Mi Band series has been a bit of a quiet marvel over the last couple of years. While they're far from the most sophisticated devices on the market, the fact remains that they're incredibly affordable and do a surprisingly great job of tracking your fitness.

The Mi Band 4 released last year, continuing the range's iteration, and it looks like Xiaomi is unsurprisingly working on a fifth version, too. The Mi Band 5 has, in fact, just had a couple of images leak which appear to show some minor changes in design and usage. 

The pictures, if they're genuine, show that the fundamental design language of the tracker, which slips into a silicone strap for your wrist, hasn't changed, although the display size has clearly been increased slightly - possibly up to 1.2 inches from the older version's 0.95 inches.

As with the Mi Band 4, the next-generation tracker looks like it'll be charged using a small dock, rather than a cable. It's a bit of a toss-up, to be honest, as to whether you prefer the ubiquity of an easily-found cable or the ease of a quick charging dock. 

The images don't reveal much else, but there have been rumours about the Mi Band 5 circulating for months. One of them estimates its likely cost at around CNY 200 (£23/$28), somehow chopping off a chunk from the £35 price point at which the Mi Band 4 debuted, which was already extremely impressive. 

It's also rumoured that the Mi Band 5 will bring a form of NFC that can be used worldwide, rather than just in China like previous generations, which would also be a good boost for its international prospects, letting users pay for things in shops with their band (if and when that becomes the norm again). Finally, the Mi Band 5 might even include Amazon Alexa support, which would be another surprising feat if it can indeed manage to keep its cost so low. 

There's no official word from Xiaomi on the device, for now, so exactly when we can expect more details remains unclear. 

Writing by Max Freeman-Mills.