The OnePlus 9 series is expected to appear in mid-March this year. It's also rumoured that those who pre-order one - when it's viable to do so - will be rewarded with bundled earphones, in the form of the Buds Z.

This early-bird promotion sounds likely to us, too, as the previous OnePlus 8 series rewarded those who pre-ordered with a pair of Bullets Wireless Z earphones and wireless charging pad.

The leak, posted on Voice by reputable leakster Evan Blass, details which reward pre-order gift you'll get dependent on handset: "Specifically, OnePlus 9 customers will get a free set of regular Buds Z, while OnePlus 9 Pro buyers will be treated to the Steve Harrington Edition," writes Blass.

So what can you expect of the OnePlus 9 series? As we outline in our round-up rumours feature, link above, there are a number of handsets expected - though perhaps not all at the same time. There's the OnePlus 9, 9 Pro, and possibly OnePlus 9E, OnePlus Lite, or OnePlus 9R.

OnePlus has a strong relationship with putting high-end Qualcomm mobile platforms into its smartphones, too, so we're anticipating the Snapdragon 888 to feature - but at sub-flagship pricing (which is still to be confirmed). That will power the 6.5-inch LCD - or larger 6.7-inch AMOLED in the Pro - at a variable high refresh rate of 120Hz.

The OnePlus 9 series is also expected to introduce the Hasselblad-branded camera setup - of which not a huge amount of detail is yet known, but it's a big differentiator for the brand.

We'll find out more in the coming days and weeks, no doubt, so keep your eyes peeled OnePlus fans - as that pre-order could prove extra valuable.