Here's a glimpse at the Microsoft Lumia 550 (via @evleaks), the upcoming budget handset that runs Windows 10.
As you'd expect from a budget model, the 550's specs are pretty unremarkable. It has a 4.7in AMOLED screen with a resolution of 1,280x720 pixels.
Inside is a Qualcomm Snapdragon 210 chipset along with a quad-core 1.1GHz CPU and the Adreno 304 GPU. This partners with 1GB of RAM.
Storage-wise, we're looking at 8GB of internal space, plus a microSD card slot.
It's not known whether the device will make an appearance at Tuesday's event, but it's highly likely. Microsoft said in the invite that it has "some exciting news to share about Windows 10 devices", so it would make sense to launch them all at once.
The Lumia 950 and 950 XL are much more high-end than the Lumia 550. According to this week's earlier leak, the 950 XL boasts a 5.7in WQHD screen, while the 950's is 5.2in with the same resolution. Both have 20-megapixel cameras with Carl Zeiss optics, and 32GB of storage plus up to 2TB using a microSD card.
Read more: Windows 10 review
The 950 XL is rumoured to support the Surface Pen.
We're also expecting to see a new Microsoft Surface tablet unveiled on Tuesday. We'll bring you all the news as it happens.