Answer to "Upgrade airport card to 802.11ac"Yes, it works. I don’t know if it makes a difference in the networking speed, but it does add the ability to unlock the Macbook with an Apple Watch, and is almost completely seamless aside from the caveats listed below. The part number to search for is: BCM94360CSAX I’ve found them on Amazon, eBay, and other sources. The two caveats on this: (1) Any apps that you’ve downloaded from the App Store seem to be tied to the MAC address, and you’ll have to authenticate at launch and/or re-download any apps from there. (2) If you bring it in for service at the Apple Store, their diagnostic tools seem to think that the Bluetooth is broken and they might replace the card. This happened to me when I had them replace the battery, so I had to get a new replacement card, install it, and re-authenticate the apps as above.