Metal core temples & spring hinges
Two construction details separate some of our frames from the rest. Here's what they are, in plain terms — and exactly which pairs have them.
Metal core temples
The temples (the arms) have a metal core running inside the plastic. It does two things: the arm resists snapping when it gets bent, and it holds an adjustment instead of springing back to the wrong shape. If you've ever had a pair where one arm slowly went its own way, that's what a metal core is there to stop.
Spring hinges
A spring hinge lets the temple flex outward past its normal stopping point and pull itself back. Two benefits: the frame tolerates a wider range of head shapes without being re-bent, and the hinge takes the strain when a pair gets pulled off one-handed — the single most common way glasses break.
They're not the same thing
A frame can have one without the other. We list them separately because we don't think you should have to guess which one you're getting.
Which pairs have them
Right now, both features are on the polarized versions of these five styles — Brody, Ryan, Briar, Zephyr and Vale.
Please read this bit: each of those styles also comes in a non-polarized version at a lower price, on the same product page. The non-polarized versions are built differently and do not have the metal core or the spring hinges. Check the construction details on the product page for the exact colour and lens you're choosing.