Project Fi is now offering data-only SIM cards for use with tablets and other devices. You can order a data-only SIM if you have already activated Fi service, and tablets with these cards will have the same data price as your phone, $10 per gigabyte. When checking your data usage, it will be broken down by device once you install a data-only SIM.

At least initially, the list of devices that work with Project Fi's data-only SIM cards is fairly limited:

  • Nexus 7 - K009 (US LTE)
  • Nexus 9 - 0P82300 (US LTE)
  • iPad Air 2 - Model A1567
  • iPad mini 4 - Model A1550
  • Galaxy Tab S - Model SM-T807V

Project Fi's support page says that the data-only SIM could work in other devices (just make sure they're T-Mobile compatible), but beyond the above list the carrier won't be inclined to support or help you with issues if you choose to use a non-approved device. The page even goes so far as to say you could use the data-only SIM in a second phone, if you wish to just have data and not calls or texts.

As for other limitations, you can add up to nine data-only SIM cards to your account, though you can use the same card in multiple devices. Additionally, you cannot tether from a device with a data-only SIM. The ability to order these cards will be rolling out gradually to existing Fi users, and the option should appear in the "account" tab of the Project Fi website in the next couple of days.

Source: Project Fi (1), (2)