Square acetate frames like the Rx4354V use a longer 145mm temple than most of the metal styles in this range, matched to the same acetate front. Acetate has some flex but no real give in length, so an aftermarket arm cut to the wrong mark still leaves the frame sitting unevenly.

Acetate can develop a fine crack near the hinge screw hole well before the front shows any wear, since that's the point taking the most repeated stress from folding. A cracked temple arm, not a damaged front, is the usual reason to replace arms on the Rx4354V. Catching that crack early and swapping in a compatible 145mm arm avoids the risk of it snapping mid-wear. It's worth inspecting the hinge area closely under good light, since a hairline crack in acetate can be easy to miss at first glance.