1) Press the little button on the inside of the temple next to the hinge (pictured).
2) Pull the arm away from the frame. Don’t be afraid to give it a good tug.
3) Grab the new arm and slide the little metal bar into the slot; apply pressure until you hear a snap.
4) Press down on that little button to lock it in place.
And boom. You have changed the arms on your Oakley Crosslinks.