If you have an old Thunderbolt Display and a 2017 or 2018 MacBook Pro, I can’t recommend this $20 cable too highly. It allows you to recharge your laptop using the Thunderbolt Display’s Magsafe connector, which means you don’t have to take your laptop’s power adapter out of your bag.1

  1. It’s also a useful cable if you have some old power adapters lying around that are based on the old Magsafe connection. This cable will make those power adapters compatible with your new MBP. ↩︎