The 'Flip Out' in RB3461's name refers to lenses that flip up rather than the temple folding, so the arm itself is a standard 140mm metal square-front hinge — the spec this aftermarket pair is built to. It's a detail worth clearing up, since 'folding' and 'flip out' get confused with each other but describe different mechanisms on different parts of the frame.

Square metal fronts like the 3461's put the hinge at a slightly wider angle than a round or oval front does, which spreads the stress differently but doesn't make the joint noticeably more or less durable. The arm's most common failure point is still the hinge screw loosening from repeated use, followed by the tip sleeve hardening with age. Replacing the arm addresses either issue without needing to touch the flip-up lens mechanism.