https://arstechnica.com/gadgets/2018/07/fcc-filings-give-further-credence-to-new-400-surface-reports/

Earlier this year, there were reports that Microsoft plans to make a new attempt at producing a low-price Surface tablet. Some new FCC filings spotted by WinFuture suggest that this tablet does indeed exist and that Microsoft has sought the necessary regulatory approval to bring it to market.

The FCC paperwork doesn't include pictures or full specs of the device—those parts are kept confidential for now—but it does disclose a few details that give some hints about the new device.