Specs-wise, the MRW-S3 uses a USB 3.1 Gen2 interface, and has both USB-A and USB-C ports that are able to take advantage of the lightning-fast transfer speeds that are accommodated by the hub. Of course, as a card reader, the hub only comes with a UHS-II SDXC and micro SDXC card slots. There’s also a USB-C port that’s used to connect the hub to the PC. In terms of speed, the MRW-S3 also has a separate USB PD port that is capable delivering sequential read and write speeds of up to 1000MB/s while also delivering 100W of power at the same time. So you don’t lose out a port in the process. More importantly, the hub also has a HDMI port built-in that is capable of outputting video to a display that supports 4K resolution, but at just 30 fps.
At the time of writing, Sony already lists the MRW-S3 on its official global page, and that it will be available sometime in the Fall of 2019. However, there is still no official pricing for the hub. (Source: Sony via Sony Addict, PetaPixel)
