When Apple announced the iPhone 15 Pro and Pro Max last fall, the company surprised everyone by putting a Thread radio in its top-of-the-line smartphones. Now, it turns out Apple also quietly added this important smart home radio to several new Macs and iPads released since September 2023.

While the company doesn’t list Thread on the specs of any of these products, FCC reports indicate that many of Apple’s latest devices have had Thread radios tested for compliance. Generally, you don’t test a radio that’s not there.

We found evidence of Thread testing in the following models:

The Verge reached out to Apple to confirm these findings and ask if the Thread radios are inactive — which could explain why they’re not listed on the products’ specs. Apple did not respond to multiple requests for comment.

The FCC requires manufacturers to list every radio contained in a device and to test them in every possible scenario to make sure they comply with its transmission regulations. Tom Sciorilli, director of certification for Thread Group, told The Verge that the FCC reports reference FCC 15.247, “which confirms the device will essentially ‘stay in its lane’ and not interfere with other radios when operating.” The reports we found are tests of the IEEE 802.15.4 transmitter functionality — 802.15.4 is the radio standard Thread runs on. While it supports a number of technologies, the reports mention Thread explicitly.

So why is it there? The Apple Home app runs on Macs and iPads, and Thread radios could allow them to communicate directly with smart home devices and act as Thread border routers. It’s possible Apple is planning to turn your Mac or iPad into a home hub, but iPads used to be home hubs, and the company discontinued that capability for its new Apple Home architecture. Those iPads didn’t have Thread radios, though.

The announcement for the iPhone 15 Pro and Pro Max only briefly mentioned the Thread radio, saying it was “opening up future opportunities for Home app integrations.” It seemed perhaps even Apple didn’t know exactly why it was there, which makes futureproofing the most obvious answer. Tri-band radio chips that bundle Wi-Fi, Bluetooth, and Thread are  becoming more popular (Silicon Labs, NXP, and Murata all make them), so it may have simply been easier to include Thread than not.

As an IP-based wireless protocol with low power and low latency, Thread would make a lot of sense outside of the smart home, too. It could be used for connecting peripherals like smart watches, medical and fitness devices, and even AirTags, keyboards, and mice to your computer, smartphone, or iPad.

Whatever those “future opportunities” turn out to be, it seems clear this wireless protocol Apple is threading across all of its devices will play a central role.