At 145mm, the RB4354's acetate temple runs longer than the metal styles in this catalogue, matched to the model's square acetate front. A compatible replacement needs to hold that length and the acetate build, since a shorter arm changes how the frame sits well before it becomes visually obvious.

The RB4354 shares its 145mm acetate temple length with the RX4354V, its optical counterpart: the sunglass and eyeglass versions use the same arm dimensions, just built around different lenses. Ordering by the exact model keeps the fit consistent either way, and it means a compatible aftermarket arm sourced for one version will generally suit the other too, provided the acetate finish matches. Buying both arms as a pair, even if only one has failed, keeps the fit even on both sides going forward and avoids mismatched wear later on.