Project Fi is Google’s specialized wireless service designed primarily for Google’s own phones. It doesn’t get much attention because, in order to use it, your main phone pretty much has to be either a Google Pixel or a Nexus device. It hasn’t kept up with the trend of unlimited data that other carriers are doing now, but it does have a refreshingly simple business model.

Here’s how it works, if you don’t know: you pay $20 per month for your phone and $10 per GB of data that you use. That’s pretty much it. Additional phones are $15 per month and use the same data bucket. If you don’t use the data, you just pay the base rate of $20. If you use more than you planned, your “overages” are just charged at that $10 / GB rate.

Fi also has another feature that I love that Google doesn’t get much credit for: you can order free, data-only SIM cards and slap them into whatever device you want at no extra charge — it just pulls from your usual data bucket. Google announced this deal alongside support for iPads and other devices back in late 2015, but I’m only now realizing how great it is.

Project Fi is an MVNO, which means Google doesn’t actually own the towers or the network you connect to, it leases time from actual carriers. In Fi’s case, it’s T-Mobile and Sprint. I’ve only ever really seen it connect to T-Mobile and the data-only SIM only works on T-Mobile. I felt that all of this is necessary to point out because if you’re thinking of switching to Fi, you should know that their coverage might not fit your needs.

I need data connectivity to do my job, especially when I’m reporting at events. And for me, that means having access to more than one wireless carrier just in case. So while my main phone is Verizon, I also keep a Project Fi phone around as a backup for tethering.

Which brings me to the data-only SIM card. If I have a gadget (like the iPad Pro I’m using now) with a SIM card slot, it means I can use LTE on it directly rather than fuss around with turning on my phone’s tethering. It’s much more convenient, but it’s also great because I’m not draining the batteries on two different devices just so I can have internet access on one of them.

It makes me wish more devices had LTE options. Now that I know it won’t cost me a monthly fee to have LTE in a tablet, I want the same option in my laptop. There’s a very real chance it’s going to help determine my next computer purchase.

Because it doesn’t cost any extra, I can put Fi data-only SIMs in all sorts of stuff. Grab an old phone that’s sitting a drawer, put a SIM in it, and now you have a backup data device. I’m currently hunting around for a good, unlocked mobile hot spot with a big battery to replace my usual battery backup. It’s a thing I want now, I want to LTE all the things.

Don’t forget, though: it’s a data-only SIM. That means you can’t use the proper phone functions without some (sort of hacky) Google Dialer / Hangouts workarounds. (But for a secondary device, it hardly seems necessary.) You also may have to futz around with the APN settings to get a device to connect, but a surprising number of devices “just work,” including the iPad.

Maybe someday Google will stop treating Fi like a side project and make it directly available and easy to set up on more than just its own phones. In the meantime, it’s my favorite way to add LTE to my devices. If I don’t use them, they don’t cost me anything. But I have a feeling I’ll be using them a lot more now.