The Colonel is Ray-Ban's rectangular take on a classic pilot-style metal frame, and the RB3560 version runs a 140mm arm — the length and metal build this compatible pair matches. Its rectangular hinge mount sits differently from the round-front models in Ray-Ban's metal range, so an arm built for those won't seat the same way here even at an identical 140mm length.

Rectangular metal frames with a pronounced bridge detail, like the Colonel, tend to put a bit more leverage through the hinge each time the arm swings open, simply because the front is heavier than a plain round or oval shape. Over enough cycles that shows up as a hinge that no longer holds its angle firmly, well before the arm itself bends or the metal finish wears through. That's the point at which replacing the arm makes more sense than repeated tightening.