RB3574N Blaze Round pairs a plastic front with 140mm metal arms curved to match the round shape, and this aftermarket set follows that same curve rather than the straighter arm used on Ray-Ban's square or rectangular lines. Getting the curve right matters more on round fronts, where the arm has to follow the frame's arc all the way to the hinge, rather than meeting it at a flat angle like a square-fronted model would.

Round metal-armed frames tend to develop play at the hinge before the curve itself loses shape, since metal holds its bend well but the screw connection is the weak point with repeated folding. If the arms feel loose side to side rather than just needing a temple-tip adjustment, that's the hinge screw, and it's a five-minute fix rather than a reason to replace the frame. It's also worth confirming both arms curve by the same amount once fitted, since a rounded front shows an uneven pair more than a straight one would.

Frequently asked questions

How do I know these arms will fit my Ray-Ban frame?

These arms are made specifically for the 3574, matching its 140mm length and Round hinge design, so they attach to your existing screws and hinge without any filing or adjustment needed.

What material are the arms made from, and will the color match my frame?

The arms are molded in an acetate or metal finish that matches the Round style of the 3574 closely, though very slight shade variation is possible since they're independently produced as separate aftermarket parts rather than cut from the same batch as the frame.

My hinge feels loose — will new arms fix that, or is it the frame that's worn?

A new 140mm arm includes its own hinge barrel, so if the wobble is coming from worn threading on the arm side of the 3574, replacing it usually restores a snug, tight fold.

Can I replace just one arm, or do I have to buy both?

You can order a single side if only one arm on your 3574 is broken or scratched, or buy the pair if both need replacing — either way they match the 140mm length exactly.