Round-bodied despite its browline design, the RB4246 Clubround uses a 145mm acetate temple built to match the front's curve. A compatible replacement needs to follow that same curve as well as the length, since a straighter aftermarket arm can still close at the hinge while sitting oddly against the rounded front.

The temple tip, the small piece behind the ear, is thinner than the rest of the arm and is usually the first part to chip or wear through on an acetate frame like this one. Once that tip goes, the whole arm typically needs replacing rather than just the end piece. It's worth checking there before assuming the whole RB4246 needs more extensive work. A quick comparison against a clear photo of the frame's finish is worth doing before ordering, since acetate tones can vary subtly between batches.