The Ray-Ban RB3611 uses a rectangular metal front on 140mm metal arms, and this aftermarket pair matches both the length and the straight-line profile so it hinges into the front exactly where the factory temple did. All-metal rectangular frames like this one rely on a clean, flat arm line, so a slightly curved substitute would sit visibly wrong against the front, since there's no rounded edge to disguise the mismatch.

Rectangular metal frames typically wear evenly along the arm but concentrate stress at the hinge corner, where the straight front meets the pivot. Keeping that screw snug matters more here than on curved styles, since a loose hinge on a rectangular frame tends to show as a visible gap rather than just a wobble. Checking the corner where the arm meets the front is usually a faster way to catch early wear than watching the arm's midsection.