140mm is a shorter arm than the 145mm used on many of Ray-Ban's other round-metal models, and it's what the RX3947V Round Gaze takes — the length this aftermarket pair is cut to, in the same metal construction as the frame's own arms. Round Gaze's round front pairs specifically with that 140mm figure, so a 145mm round-metal arm from elsewhere in the line won't sit right.

Shorter metal arms like this one have a smaller margin for the fit to be exactly right — even a few millimeters off at the hinge can leave the temple sitting either too tight behind the ear or slightly loose. That's the main reason to confirm the 140mm figure against the arm you're replacing rather than going by the general 'round metal Ray-Ban' description alone. Once the length is right, wear and care are the same as any slim metal arm: mainly the hinge screw and tip sleeve over time.

Frequently asked questions

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 3947, replacing it usually restores a snug, tight fold.

Is it worth buying new arms instead of a whole new frame?

Replacing both arms on the 3947 costs from €26.95 with free worldwide shipping, far less than a new frame, and it's backed by a 3-year warranty against manufacturing defects on the 140mm hardware itself.

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 3947 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.

Are these official Ray-Ban replacement parts?

These are compatible aftermarket arms, independently produced to match the 3947's hinge and 140mm length. They aren't manufactured or supplied by Ray-Ban, just built to the same measurements so they attach correctly.